As filed with the Securities and Exchange Commission on July 20, 2005

SECURITIES AND EXCHANGE COMMISSION

SOUTHWEST AIRLINES CO.

2702 Love Field Drive, Dallas, TX 75235
214/792-4000
(Address, Including Zip Code, and Telephone Number,
Including Area Code, of Registrant’s Principal Executive Offices)

LAURA WRIGHT
Senior Vice President — Chief Financial Officer
Southwest Airlines Co.
2702 Love Field Drive, Dallas, TX 75235
214/792-4459
(Name, address, including zip code, and telephone
number, including area code, of agent for service)

DEBORAH ACKERMAN
Vice President — General Counsel
Southwest Airlines Co.
2702 Love Field Drive, Dallas, TX 75235
214/792-4665

     Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this Registration Statement.

     If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, check the following box. o

     If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box. þ

     If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

     If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

     If delivery of the prospectus is expected to be made pursuant to Rule 434, check the following box. o

CALCULATION OF REGISTRATION FEE

(2) In no event will the aggregate initial offering price of all securities issued from time to time pursuant to this registration statement exceed $995,218,565 or the equivalent thereof in one or more foreign currencies or composite currencies, including the euro.

(3) Estimated solely for purposes of determining the registration fee pursuant to Rule 457(o) under the Securities Act of 1933.

Pursuant to Rule 429 under the Securities Act of 1933, as amended, the prospectuses herein are combined prospectuses that also relate to Registration Statement No. 333-100861 previously filed by Southwest Airlines Co. as to which securities having an aggregate offering price of $344,781,435 remain unsold, and for which the registration fee was previously paid. Upon effectiveness, this Registration Statement shall constitute Post-Effective Amendment No. 1 to Registration Statement No. 333-100861.

     THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(A), MAY DETERMINE.

EXPLANATORY NOTE

     This Registration Statement contains two separate forms of prospectuses to be used in connection with offerings of Debt Securities and Pass Through Certificates.

The information in this prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell securities and it is not soliciting an offer to buy securities in any state where the offer or sale is not permitted.

                                                                                                                           SUBJECT TO COMPLETION, DATED JULY 20, 2005

PROSPECTUS

Southwest Airlines Co.

DEBT SECURITIES

     By this prospectus, we may offer from time to time up to $1,340,000,000 of our unsecured, non-convertible, debt securities. When we offer debt securities, we will provide you with a prospectus supplement describing the terms of the specific issue of debt securities, including the offering price of the debt securities.

     You should read this prospectus and the prospectus supplement relating to the specific issue of debt securities carefully before you invest.

     Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined that this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is                                         , 2005.

TABLE OF CONTENTS

     You should rely only on the information contained in this prospectus or any prospectus supplement or information contained in documents which you are referred to in this prospectus or any prospectus supplement. We have not authorized anyone to provide you with information different from that contained in this prospectus or any prospectus supplement. We are offering to sell the debt securities only in jurisdictions where offers and sales are permitted. The information contained in this prospectus or any prospectus supplement is accurate only as of the date on the front of those documents, regardless of the time of delivery of the documents or any sale of the debt securities.

ABOUT THIS PROSPECTUS

     This prospectus is part of two registration statements that we filed with the Securities and Exchange Commission utilizing a shelf registration process. Under this shelf process, we may sell the securities described in this prospectus in one or more offerings up to a total offering amount of $1,340,000,000. This prospectus provides you with a general description of the debt securities we may offer.

     Each time we sell debt securities, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement may also add, update or change information contained in this prospectus. You should read both this prospectus and any prospectus supplement together with additional information described in the section entitled “Where You Can Find More Information.”

     For more detail, you should read our registration statements and the exhibits filed with our registration statements.

     In this prospectus, references to “Southwest,” “we,” “us” and “our” mean Southwest Airlines Co.

(i)

FORWARD-LOOKING STATEMENTS

     This prospectus includes or incorporates by reference “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, which represent our expectations or beliefs concerning future events. When used in this prospectus and the incorporated documents, the words “expects,” “plans,” “anticipates” and similar expressions are intended to identify forward-looking statements. All forward-looking statements in this prospectus are based upon information available to us on the date of this prospectus. We undertake no obligation to update publicly or revise any forward-looking statement, whether as a result of new information, future events or otherwise. Forward-looking statements involve risks and uncertainties that could cause actual results to differ materially from historical experience or our expectations. Additional information concerning these and other factors is contained in our SEC filings, including but not limited to our Forms 10-K, 10-Q and 8-K.

(ii)

THE COMPANY

     Southwest Airlines Co. is a major domestic airline that provides point-to-point, low-fare service. Historically, routes served by Southwest had been predominantly short-haul, with high frequencies. In recent years, we have complemented this service with more medium to long-haul routes, including transcontinental service. We were incorporated in Texas in 1967 and commenced Customer Service on June 18, 1971, with three Boeing 737 aircraft serving three Texas cities — Dallas, Houston, and San Antonio. At year-end 2004, we operated 417 Boeing 737 aircraft and provided service to 60 airports in 59 cities in 31 states throughout the United States.

     Additional information about us is included in our reports and other documents incorporated by reference in this prospectus. See “Where You Can Find More Information.”

     Our principal executive offices are located at 2702 Love Field Drive, P.O. Box 36611, Dallas, Texas 75235, and our telephone number is (214) 792-4000.

USE OF PROCEEDS

     We intend to use the net proceeds from the offering of the debt securities for general corporate purposes, unless otherwise specified in the prospectus supplement relating to a specific issuance of debt securities. Such general corporate purposes may include, among other possible uses, the repayment of short-term or long-term indebtedness and capital expenditures.

RATIOS OF EARNINGS TO FIXED CHARGES

     The following table sets forth our historical ratios of earnings to fixed charges for the periods indicated:

     Earnings represent:

     Fixed charges include:

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DESCRIPTION OF DEBT SECURITIES SOUTHWEST MAY OFFER

     We will issue the debt securities under a contract called the indenture between us and The Bank of New York Trust Company, N.A., which acts as trustee. We may issue as many distinct series of debt securities under the indenture as we wish.

     The trustee has two main roles. First, the trustee can enforce your rights against us if we default. There are some limitations on the extent to which the trustee acts on your behalf, described later in this section under “Default and Related Matters — Remedies If an Event of Default Occurs.” Second, the trustee performs administrative duties for us, such as sending you interest payments, transferring your debt securities to a new buyer if you sell and sending you notices.

     The indenture and its associated documents contain the full legal text of the matters described in this section. The indenture and the debt securities are governed by Texas law. A copy of the indenture may be obtained from us as described below under “Where You Can Find More Information.”

     This section summarizes the material terms of the debt securities that we expect will be common to all series, although the prospectus supplement which describes the terms of each series of debt securities may also describe differences with the material terms summarized here.

     Because this section is a summary, it does not describe every aspect of the debt securities. This summary is subject to and qualified in its entirety by reference to all the provisions of the indenture, including definitions of certain terms used in the indenture. In this summary, we describe the meaning for only the more important terms. You must look to the indenture for the most complete description of what is described in summary form in this prospectus.

     This summary also is subject to and qualified by reference to the description of the particular terms of your series described in the prospectus supplement. Those terms may vary from the terms described in this prospectus. The prospectus supplement relating to each series of debt securities will be attached to the front of this prospectus. There may also be a further prospectus supplement, known as a pricing supplement, which contains the precise terms of debt securities you are offered.

     We may issue the debt securities as original issue discount securities, which will be offered and sold at a substantial discount below their stated principal amount. The prospectus supplement relating to the original issue discount securities will describe federal income tax consequences and other special considerations applicable to them. The prospectus supplement relating to specific debt securities will also describe any special considerations and certain additional tax considerations applicable to such debt securities.

     In addition, the specific financial, legal and other terms particular to a series of debt securities are described in the prospectus supplement and any pricing supplement relating to the series. The prospectus supplement relating to a series of debt securities will describe the following terms of the series:

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Legal Ownership

     Street Name and Other Indirect Holders. Investors who hold debt securities in accounts at banks or brokers will generally not be recognized by us as legal holders of debt securities. This is called holding in street name. Instead, we would recognize only the bank or broker, or the financial institution the bank or broker uses to hold its debt securities. These intermediary banks, brokers and other financial institutions pass along principal, interest and other payments on the debt securities, either because they agree to do so in their customer agreements or because they are legally required to. If you hold debt securities in street name, you should check with your own institution to find out:

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     Direct Holders. Our obligations, as well as the obligations of the trustee and those of any third parties employed by us or the trustee, run only to persons who are registered as holders of debt securities. As noted above, we do not have obligations to you if you hold debt securities in street name or other indirect means, either because you choose to hold debt securities in that manner or because the debt securities are issued in the form of global securities as described below. For example, once we make payment to the registered holder, we have no further responsibility for the payment, even if that holder is legally required to pass the payment along to you as a street name customer but does not do so.

Global Securities

     What is a Global Security? A global security is a special type of indirectly held security, as described above under “Street Name and Other Indirect Holders.” If we choose to issue debt securities in the form of global securities, the ultimate beneficial owners can only be indirect holders. We do this by requiring that the global security be registered in the name of a financial institution we select and by requiring that the debt securities included in the global security not be transferred to the name of any other direct holder unless the special circumstances described below occur. The financial institution that acts as the sole direct holder of the global security is called the depositary. Any person wishing to own a debt security must do so indirectly by virtue of an account with a broker, bank or other financial institution that in turn has an account with the depositary. The prospectus supplement indicates whether your series of securities will be issued only in the form of global securities.

     Special Investor Considerations for Global Securities. As an indirect holder, an investor’s rights relating to a global security will be governed by the account rules of the investor’s financial institution and of the depositary, as well as general laws relating to securities transfers. We do not recognize this type of investor as a holder of debt securities and instead deal only with the depositary that holds the global security.

     If you are an investor, you should be aware that if debt securities are issued only in the form of global securities:

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     Special Situations when Global Security will be Terminated. In a few special situations described in the next paragraph, the global security will terminate and interests in it will be exchanged for physical certificates representing debt securities. After that exchange, the choice of whether to hold debt securities directly or in street name will be up to you. You must consult your own bank or broker to find out how to have your interests in debt securities transferred to your own name, so that you will be a direct holder. The rights of street name investors and direct holders in the debt securities have been previously described under “Legal Ownership” in the subsections entitled “Street Name and Other Indirect Holders” and “Direct Holders.”

     The special situations for termination of a global security are:

     The prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of debt securities covered by the prospectus supplement. When a global security terminates, the depositary (and not us or the trustee) is responsible for deciding the names of the institutions that will be the initial direct holders.

     IN THE REMAINDER OF THIS DESCRIPTION “YOU” MEANS DIRECT HOLDERS AND NOT STREET NAME OR OTHER INDIRECT HOLDERS OF DEBT SECURITIES. INDIRECT HOLDERS SHOULD READ THE PREVIOUS SUBSECTION ENTITLED “STREET NAME AND OTHER INDIRECT HOLDERS.”

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Overview of Remainder of this Description

     The remainder of this description summarizes:

Additional Mechanics

     Form, Exchange and Transfer. The debt securities will be issued:

     You may have your debt securities divided into more debt securities of smaller denominations or combined into fewer debt securities of larger denominations, as long as the total principal amount is not changed. This is called an exchange.

     You may exchange or transfer debt securities at the office of the trustee. The trustee acts as our agent for registering debt securities in the names of holders and transferring debt securities. We may change this appointment to another entity or perform these functions ourselves. The entity performing the role of maintaining the list of registered holders is called the security registrar. It will also perform transfers.

     You will not be required to pay a service charge to transfer or exchange debt securities, but you may be required to pay for any tax or other governmental charge associated with the exchange or transfer. The transfer or exchange will only be made if we and the security registrar are satisfied with your proof of ownership.

     If we have designated additional transfer agents, they are named in the prospectus supplement. We may cancel the designation of any particular transfer agent. We may also approve a change in the office through which any transfer agent acts.

     If the debt securities are redeemable, we may block the transfer or exchange of debt securities for a period beginning 15 days before the day we mail the notice of redemption, in order to freeze the list of holders to prepare the mailing. We may also refuse to register transfers or exchanges of debt securities selected for redemption, except that we will continue to permit transfers and exchanges of the unredeemed portion of any debt security being partially redeemed.

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     Payment and Paying Agents. We will pay interest to you if you are a direct holder listed in the trustee’s records at the close of business on a particular day in advance of each due date for interest, even if you no longer own the debt security on the interest due date. That particular day, usually about two weeks in advance of the interest due date, is called the regular record date and is stated in the prospectus supplement. Holders buying and selling debt securities must work out between them how to compensate for the fact that we will pay all the interest for an interest period to the one who is the registered holder on the regular record date. The most common manner is to adjust the sales price of the securities to pro rate interest fairly between buyer and seller. This prorated interest amount is called accrued interest.

     We will pay interest, principal and any other money due on the debt securities at the corporate trust office of the trustee in Dallas, Texas. You must make arrangements to have your payments picked up at or wired from that office. We may also choose to pay interest by mailing checks. However, if the debt securities are represented by a global security, we will make payments to the depositary by wire.

     STREET NAME AND OTHER INDIRECT HOLDERS SHOULD CONSULT THEIR BANKS, BROKERS OR OTHER FINANCIAL INSTITUTIONS FOR INFORMATION ON HOW THEY WILL RECEIVE PAYMENTS.

     We may also arrange for additional payment offices, and may cancel or change these offices, including the use of the trustee’s corporate trust office. These offices are called paying agents. We may also choose to act as our own paying agent. We must notify you of changes in the paying agents for any particular series of debt securities.

     Notices. We and the trustee will send notices regarding the debt securities only to direct holders, using their addresses as listed in the trustee’s records.

     Regardless of who acts as paying agent, all money paid by us to a paying agent that remains unclaimed at the end of two years after the amount is due to direct holders will be repaid to us. After that two-year period, you may look only to us for payment and not to the trustee, any other paying agent or anyone else.

Special Situations

     Mergers and Similar Events. We are generally permitted to consolidate or merge with another entity. We are also permitted to sell or convey all or substantially all of our assets to another entity. However, we may not take any of these actions unless all of the following conditions are met:

     Where we consolidate or merge out of existence or sell or convey all or substantially all of our assets, the other entity must be organized under the laws of a state or under federal law, and it must agree to be legally responsible for the debt securities.

     Immediately after the merger, sale of assets or other transaction, we must not be in default on the debt securities. A default for this purpose would also include any event that would be an event of default if the requirements for giving us default notice or our default having to exist for a specific period of time were disregarded.

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Modification and Waiver

     There are three types of changes we can make to the indenture and the debt securities.

     Changes Requiring Your Approval. First, there are changes that cannot be made to your debt securities without your specific approval. Following is a list of those types of changes:

     Changes Requiring a Vote. The second type of change to the indenture and the debt securities is the kind that requires a vote in favor by the holders of debt securities owning at least 66-2/3% of the principal amount of the particular series affected. Most changes fall into this category, except for clarifying changes and certain other changes that would not adversely affect the interests of holders of the debt securities described in the next paragraph. We may obtain a waiver of a past default from the holders of debt securities owning a majority of the principal amount of the particular series affected. However, we cannot obtain a waiver of a payment default unless we obtain an individual consent to the waiver from every holder.

     Changes Not Requiring Approval. The third type of change to the indenture and the debt securities does not require any vote by holders of debt securities. This type is limited to clarifications and certain other changes that would not adversely affect the interests of holders of the debt securities. Holders of debt securities will also not be eligible to vote if the debt securities have been fully defeased as described below under “Defeasance.”

     STREET NAME AND OTHER INDIRECT HOLDERS SHOULD CONSULT THEIR BANKS, BROKERS OR OTHER FINANCIAL INSTITUTIONS FOR INFORMATION ON HOW APPROVAL MAY BE GRANTED OR DENIED IF WE SEEK TO CHANGE THE INDENTURE OR THE DEBT SECURITIES OR REQUEST A WAIVER.

Absence of Restrictive Covenants

     The indenture does not contain any promises by us on how we will operate our business, and does not restrict our ability to incur debt or grant liens on our assets. If we determine to include such a promise for the benefit of a particular series of debt securities, such promise, or restrictive covenant, will be described in the prospectus supplement relating to that series of debt securities.

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Defeasance

     We may be completely released from our payment and other obligations on the debt securities. The following discussion of defeasance will be applicable to your series of debt securities only if we choose to have them apply to that series. If we do so choose, we will state that in the prospectus supplement.

     If there is a change in federal tax law, or if we obtain a ruling from the Internal Revenue Service, as described below, we can legally release ourselves from any payment or other obligations on the debt securities, called full or legal defeasance, if we put in place the following arrangements for you to be repaid:

     If we are able to fully defease the debt securities, as described above, you would have to rely solely on the trust deposit for repayment on the debt securities. You could not look to us for repayment.

Satisfaction and Discharge

     The indenture will cease to be of further effect as to all debt securities of any series when either:

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     Notwithstanding any satisfaction and discharge or any defeasance with respect to the debt securities of any series, your rights of transfer and exchange, your rights to replace lost, stolen or destroyed debt securities, the rights and obligations of the trustee and your rights as beneficiaries with respect to the trust funds deposited with the trustee would survive.

Default and Related Matters

     Ranking. The debt securities are not secured by any of our property or assets. Accordingly, your ownership of debt securities means you are one of our unsecured creditors. The debt securities are not subordinated to any of our other debt obligations and therefore they rank equally in contractual right of payment with all of our other unsubordinated indebtedness.

     Events of Default. You will have special rights if an event of default occurs and is not cured, as described later in this subsection.

     What is an Event of Default? The term “event of default” means any of the following:

     Remedies if an Event of Default Occurs. If an event of default has occurred and has not been cured, the trustee or the holders of at least 25% in principal amount of the debt securities of the affected series may declare the entire principal amount (or, in the case of original issue discount securities, the portion of the principal amount that is specified in the terms of the affected debt security) of all the debt securities of that series, plus accrued interest, to be due and immediately payable. This is called a declaration of acceleration of maturity. However, a declaration of acceleration of maturity may be cancelled, but only before a judgment or decree based on the acceleration has been obtained, by the holders of at least a majority in principal amount of the debt securities of the affected series.

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     Reference is made to the prospectus supplement relating to any series of debt securities which are original issue discount securities for the particular provisions relating to acceleration of the maturity of a portion of the principal amount of original issue discount securities upon the occurrence of an event of default and its continuation.

     Except in cases of default, where the trustee has some special duties, the trustee is not required to take any action under the indenture at the request of any holders unless the holders offer the trustee reasonable protection from expenses and liability, called an indemnity. If reasonable indemnity is provided, the holders of a majority of the aggregate principal amount of the securities of all series affected (voting as one class) may direct the time, method and place of conducting any lawsuit or other formal legal action seeking any remedy available to the trustee. The trustee is required, within 90 days of acquiring knowledge of a default with respect to the debt securities of any series, to give you notice of the default, unless the default has been cured or waived before it gives the notice; however, the trustee may withhold notice of any non-payment default if it determines that withholding notice is in the interest of the holders of debt securities of that series.

     Before you bypass the trustee and bring your own lawsuit or other formal legal action or take other steps to enforce your rights or protect your interests relating to the debt securities, the following must occur:

     However, you are entitled at any time to bring a lawsuit for the payment of money due on your debt security on or after its due date.

     STREET NAME AND OTHER INDIRECT HOLDERS SHOULD CONSULT THEIR BANKS, BROKERS OR OTHER FINANCIAL INSTITUTIONS FOR INFORMATION ON HOW TO GIVE NOTICE OR DIRECTION TO OR MAKE A REQUEST OF THE TRUSTEE AND TO MAKE OR CANCEL A DECLARATION OF ACCELERATION.

     We will furnish to the trustee every year a written statement of certain of our officers certifying that to their knowledge we are in compliance with the indenture and the debt securities, or else specifying any default and indicating the nature and status of the default.

Concerning the Trustee

     The trustee under the indenture is The Bank of New York Trust Company, N.A.

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     The indenture contains certain limitations on the right of the trustee, should it become a creditor of ours, to obtain payment of claims in certain cases, or to realize for its own account on certain property received in respect of any such claim as security or otherwise. The trustee will be permitted to engage in certain other transactions; however, if after an event of default has occurred and is continuing, the trustee acquires any conflicting interest (as described in the indenture) it must eliminate such conflict or resign.

PLAN OF DISTRIBUTION

     We may sell debt securities:

     Any underwriter or agent involved in the offer and sale of any series of the debt securities will be named in the prospectus supplement.

     The prospectus supplement for each series of debt securities will describe:

     Only the agents or underwriters named in a prospectus supplement are agents or underwriters in connection with the debt securities being offered by that prospectus supplement.

     Underwriters, agents and dealers may be entitled, under agreements with us, to indemnification against certain civil liabilities, including liabilities under the Securities Act of 1933.

     Underwriters to whom debt securities are sold by us for public offering and sale are obliged to purchase all of those particular debt securities if any are purchased. This obligation is subject to certain conditions and may be modified in the applicable prospectus supplement.

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     Each series of debt securities will be a new issue of securities and will not have an established trading market. Unless otherwise indicated in the applicable prospectus supplement, we will not list any series of debt securities on an exchange. No assurance can be given that you will be able to resell any debt securities that you may purchase.

     Underwriters, dealers or agents may engage in transactions with, or perform services for, us or our affiliates in the ordinary course of business.

VALIDITY OF THE DEBT SECURITIES

     Unless otherwise indicated in the applicable prospectus supplement, the validity of the debt securities offered hereby will be passed upon for us by Deborah Ackerman, Vice President — General Counsel.

EXPERTS

     The consolidated financial statements of Southwest Airlines Co. included in Southwest Airlines Co.’s Annual Report (Form 10-K) for the year ended December 31, 2004, and Southwest Airlines Co.’s assessment of the effectiveness of internal control over financial reporting as of December 31, 2004 included therein, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in its reports thereon, included therein, and incorporated herein by reference. Such financial statements and management’s assessment have been incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

     We file annual, quarterly and special reports, proxy statements and other information with the Securities and Exchange Commission. You may read and copy any documents we file at the SEC’s public reference room, 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the public reference room. Our SEC filings are also available to the public on the SEC’s web site at http://www.sec.gov and through the New York Stock Exchange, 20 Broad Street, New York, New York 10005, on which our common stock is listed.

     The SEC allows us to “incorporate by reference” the information we file with them, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus, and later information that we file with the SEC will automatically update and supersede this information as well as the information included in this prospectus. We incorporate by reference the documents listed below and any future filings made with the SEC under Sections 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934 (excluding any information furnished pursuant to Item 2.02 or 7.01 on any current Report on Form 8-K) until we sell all the debt securities.

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Any party to whom this prospectus is delivered, including a holder in street name, may request a copy of these filings (other than any exhibits unless specifically incorporated by reference into this prospectus), at no cost, by writing or telephoning us at the following address:

Southwest Airlines Co.
Investor Relations
P.O. Box 36611, HDQ-6FC
2702 Love Field Drive
Dallas, Texas 75235
(214) 792-4000

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The information in this prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell securities and it is not soliciting an offer to buy securities in any state where the offer or sale is not permitted.

                                                                                                                           SUBJECT TO COMPLETION, DATED JULY 20, 2005

PROSPECTUS

SOUTHWEST AIRLINES CO.
PASS THROUGH CERTIFICATES

     This prospectus relates to the issuance of Pass Through Certificates by one or more Pass Through Trusts to be formed by Southwest Airlines Co.

THE CERTIFICATES:

     The aggregate public offering price of the Certificates will not exceed $1,340,000,000.

EACH PASS THROUGH TRUST:

THE EQUIPMENT NOTES:

     This prospectus is accompanied by a prospectus supplement that includes additional information as to the particular series of Certificates being sold and the underlying Equipment Notes. Sales of Certificates may not be consummated without both this prospectus and a prospectus supplement.

     Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined that this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is                     , 2005.

TABLE OF CONTENTS

     You should rely only on the information contained in this prospectus or any prospectus supplement or information contained in documents which you are referred to in this prospectus or any prospectus supplement. We have not authorized anyone to provide you with information different from that contained in this prospectus or any prospectus supplement. We are offering to sell the pass through certificates only in jurisdictions where offers and sales are permitted. The information contained in this prospectus or any prospectus supplement is accurate only as of the date on the front of those documents, regardless of the time of delivery of the documents or any sale of the pass through certificates.

ABOUT THIS PROSPECTUS

     This prospectus is part of two registration statements that we filed with the Securities and Exchange Commission utilizing a shelf registration process. Under this shelf process, the Certificates described in this prospectus may be sold in one or more offerings up to a total offering amount of $1,340,000,000. This prospectus provides you with a general description of the Certificates that may be offered.

     Each time Certificates are sold, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement may also add, update or change information contained in this prospectus. You should read both this prospectus and any prospectus supplement together with additional information described in the section entitled “Where You Can Find More Information.”

     For more detail, you should read our registration statements and the exhibits filed with our registration statements.

(i)

     In this prospectus, references to “Southwest,” “we,” “us” and “our” mean Southwest Airlines Co.

FORWARD-LOOKING STATEMENTS

     This prospectus includes or incorporates by reference “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, which represent our expectations or beliefs concerning future events. When used in this prospectus and the incorporated documents, the words “expects,” “plans,” “anticipates” and similar expressions are intended to identify forward-looking statements. All forward-looking statements in this prospectus are based upon information available to us on the date of this prospectus. We undertake no obligation to update publicly or revise any forward-looking statement, whether as a result of new information, future events or otherwise. Forward-looking statements involve risks and uncertainties that could cause actual results to differ materially from historical experience or our expectations. Additional information concerning these and other factors is contained in our SEC filings, including but not limited to our Forms 10-K, 10-Q and 8-K.

(ii)

THE COMPANY

     Southwest Airlines Co. is a major domestic airline that provides point-to-point, low-fare service. Historically, routes served by Southwest had been predominantly short-haul, with high frequencies. In recent years, we have complemented this service with more medium to long-haul routes, including transcontinental service. We were incorporated in Texas in 1967 and commenced Customer Service on June 18, 1971, with three Boeing 737 aircraft serving three Texas cities — Dallas, Houston, and San Antonio. At year-end 2004, we operated 417 Boeing 737 aircraft and provided service to 60 airports in 59 cities in 31 states throughout the United States.

     Additional information about us is included in our reports and other documents incorporated by reference in this prospectus. Please refer to the section “Where You Can Find More Information.”

     Our principal executive offices are located at 2702 Love Field Drive, P.O. Box 36611, Dallas, Texas 75235, and our telephone number is (214) 792-4000.

SUMMARY

Certificates

     Pass through certificates are securities that evidence an ownership interest in a pass through trust. The holders of the certificates issued by a pass through trust will be the beneficiaries of that trust. For convenience, we may refer to pass through certificates as “certificates” and refer to the holder of a pass through certificate as a “certificateholder.”

     The beneficial interest in a pass through trust represented by a certificate will be a percentage interest in the property of that trust equal to the original face amount of such certificate divided by the original face amount of all of the certificates issued by that trust. Each certificate will represent a beneficial interest only in the property of the pass through trust that issued the certificate. Multiple series of certificates may be issued. If more than one series of certificates is issued, each series of certificates will be issued by a separate pass through trust.

     The property that will be held by each pass through trust will include equipment notes secured by aircraft that we own or lease. Payments of principal, premium, if any, and interest on the equipment notes owned by a pass through trust will be passed through to holders of certificates issued by that trust in accordance with the terms of the pass through trust agreement pursuant to which the trust was formed.

     If certificates of any series are entitled to the benefits of a liquidity facility or other form of credit enhancement, the prospectus supplement relating to that series will describe the terms of the liquidity facility or other form of credit enhancement. A liquidity facility is a revolving credit agreement, letter of credit, bank guarantee, insurance policy or other instrument or agreement under which another person agrees to make certain payments in respect of the certificates if there is a shortfall in amounts otherwise available for distribution. While a liquidity facility is designed to increase the likelihood of the timely payment of certain amounts due under certificates, it is not a guarantee of timely or ultimate payment.

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     The rights of a pass through trustee to receive monies payable under equipment notes held for that pass through trustee may be subject to the effect of subordination provisions contained in an intercreditor agreement described in the prospectus supplement for a series of certificates. An intercreditor agreement will set forth the terms and conditions upon which payments made under the equipment notes and payments made under any liquidity facility will be received, shared and distributed among the several pass through trustees and the liquidity provider.

     We may offer and sell up to $1,340,000,000 of aggregate initial offering price of certificates pursuant to this prospectus and related prospectus supplements in one or more offerings of certificates.

Pass Through Trusts

     We will form a separate pass through trust to issue each series of certificates. Each pass through trust will be formed by us, as creator of each pass through trust, and a national or state bank or trust company, as trustee.

     Unless otherwise stated in a prospectus supplement, Wilmington Trust Company will be the trustee of each pass through trust. For convenience, we may refer to the pass through trustee as the “trustee.”

     Each pass through trust will be governed by a trust instrument that creates the trust and sets forth the powers of the trustee and the rights of the beneficiaries. The beneficiaries of a pass through trust will be the holders of certificates issued by that trust. The trust instrument for each pass through trust will consist of a basic pass through trust agreement between us and the pass through trustee, which we refer to as the “Basic Agreement,” and a supplement to that basic agreement, which we refer to as a “pass through trust supplement.”

     When a pass through trust supplement is signed and delivered, the pass through trustee, on behalf of the related pass through trust, will enter into one or more purchase or refunding agreements, typically referred to as “note purchase agreements” or “participation agreements” under which it will agree to purchase one or more promissory notes secured by aircraft described in the applicable prospectus supplement. These secured promissory notes are referred to as “equipment notes.”

     Under the applicable note purchase agreement or participation agreement, the pass through trustee, on behalf of the related pass through trust, will purchase one or more equipment notes. The equipment notes that are the property of a pass through trust will have:

     If any portion of the proceeds of an offering of a series of certificates is not used to purchase equipment notes on the date the certificates are originally issued, those proceeds will be held for the benefit of the certificateholders. If any of the proceeds are not later used to purchase

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equipment notes by the date specified in the applicable prospectus supplement, the proceeds will be returned to the certificateholders.

Equipment Notes

     The equipment notes owned by a pass through trust may consist of any combination of:

     Leased Aircraft Notes. Except as specified in a prospectus supplement, leased aircraft notes will be issued by a bank, trust company, financial institution or other entity solely in its capacity as owner trustee in a leveraged lease transaction. In a leveraged lease transaction, one or more persons will form an owner trust to acquire an aircraft and then that owner trust will lease the aircraft to us. The investors that are the beneficiaries of the owner trusts are typically referred to as owner participants. Each owner participant will contribute a portion of the purchase price of the aircraft to the owner trust, and the remainder of the purchase price of the aircraft will be financed, or “leveraged,” through the issuance of leased aircraft notes. Leased aircraft notes may also be issued to refinance an aircraft previously financed in a leveraged lease transaction or otherwise.

     The leased aircraft notes will be issued pursuant to a separate indenture between the owner trustee and a bank, trust company, financial institution or other entity, as loan trustee. The indenture entered into in connection with the issuance of leased aircraft notes will be referred to as a “leased aircraft indenture.” The loan trustee under a leased aircraft indenture will act as a trustee for the holders of the leased aircraft notes issued under that leased aircraft indenture.

     In a leveraged lease transaction, we will pay or advance rent and other amounts to the owner trustee in its capacity as lessor under the lease. The owner trustee will use the rent payments and certain other amounts received by it to make payments of principal and interest on the leased aircraft notes. The owner trustee also will assign its rights to receive basic rent and certain other payments to a loan trustee as security for the owner trustee’s obligations to pay principal of, premium, if any, and interest on the leased aircraft notes.

     Payments or advances required to be made under a lease and related agreements will at all times be sufficient to make scheduled payments of principal of, and interest on, the leased aircraft notes issued to finance the aircraft subject to that lease. However, we will not have any direct obligation to pay principal of, or interest on, the leased aircraft notes. No owner participant or owner trustee will be personally liable for any amount payable under a leased aircraft indenture or the leased aircraft notes issued under that indenture.

     Owned Aircraft Notes. We may finance or refinance aircraft that we own through the issuance of owned aircraft notes. Owned aircraft notes relating to an owned aircraft will be issued under a separate indenture relating to that owned aircraft. Each separate indenture relating to owned aircraft notes will be between us and a bank, trust company, financial institution or other entity, as loan trustee. The indenture entered into in connection with the issuance of owned aircraft

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notes will be referred to as an “owned aircraft indenture.” Because we often refer to owned aircraft indentures and leased aircraft indentures together, we sometimes refer to them collectively as the “indentures.” The loan trustee under an owned aircraft indenture will act as a trustee for the holders of the owned aircraft notes issued under that owned aircraft indenture.

     Unlike the leased aircraft notes, we will have a direct obligation to pay the principal of, and interest on, the owned aircraft notes.

USE OF PROCEEDS

     The trustee will use the proceeds of the certificates for the purchase of one or more equipment notes. Except as set forth in a prospectus supplement for a specific offering of certificates, the equipment notes will be issued:

     General corporate purposes of Southwest may include, among other possible uses, the repayment of short-term or long-term indebtedness and capital expenditures.

     To the extent that the proceeds of any offering of certificates are not used to purchase equipment notes on the date of issuance of those certificates, the relevant proceeds will be held for the benefit of those certificateholders. If those proceeds are not used to purchase equipment notes by the date specified in the applicable prospectus supplement, they will be returned to the applicable certificateholders. See “Description of Certificates — Delayed Purchase of Equipment Notes” for a description of the procedure for delayed purchase of equipment notes.

     The prospectus supplement with respect to any offering of certificates will provide additional details with respect to the use of proceeds of those certificates, and with respect to the use of proceeds of any equipment notes to be purchased by a pass through trust.

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RATIOS OF EARNINGS TO FIXED CHARGES

     The following table sets forth our historical ratios of earnings to fixed charges for the periods indicated:

     Earnings represent:

     Fixed charges include:

DESCRIPTION OF THE CERTIFICATES

     The following summary describes the material terms of the certificates that we expect will be common to all series of certificates. We will describe the financial terms and other specific terms of any series of certificates in a prospectus supplement. To the extent that any provision in any prospectus supplement is inconsistent with any provision in this prospectus, the provision of the prospectus supplement will control.

     Because the following description is a summary, it does not describe every aspect of the certificates, and it is subject to and qualified in its entirety by reference to all the provisions of the pass through trust agreement and the applicable supplements to the pass through trust agreement. For convenience, we will refer to the pass through trust agreement between the pass through trustee and us as the “Basic Agreement,” and to the Basic Agreement as supplemented by a supplement as a “pass through trust agreement.” The form of Basic Agreement has been filed as an exhibit to the registration statement of which this prospectus is a part. The supplement to the Basic Agreement relating to each series of certificates and the forms of the other agreements described in this prospectus and the applicable prospectus supplement will be filed as exhibits to a post-effective amendment to the registration statement of which this prospectus is a part, a Current Report on Form 8-K, a Quarterly Report on Form 10-Q or an Annual Report on Form 10-K, as applicable, filed by us with the SEC.

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General

     Except as amended by a supplement to the Basic Agreement, the terms of the Basic Agreement generally will apply to all of the pass through trusts that we form to issue certificates. We will create a separate pass through trust for each series of certificates by entering into a separate supplement to the Basic Agreement. Each supplement to the Basic Agreement will contain the additional terms governing the specific pass through trust to which it relates and, to the extent inconsistent with the Basic Agreement, will supersede the Basic Agreement.

     Certificates for a pass through trust will be issued pursuant to the pass through trust agreement applicable to such pass through trust. Unless otherwise stated in the applicable prospectus supplement, each pass through certificate will be issued in a minimum denomination of $1,000 or a multiple of $1,000, except that one certificate of each series may be issued in a different denomination.

     Each certificate will represent a fractional undivided interest in the property of the pass through trust that issued the certificate. All payments and distributions made with respect to a certificate will be made only from the property owned by the pass through trust that issued the certificate. The certificates do not represent an interest in or obligation of Southwest, the pass through trustee, any of the owner trustees or loan trustees, in their individual capacities, or any owner participant. Each certificateholder by its acceptance of a certificate agrees to look solely to the income and proceeds from the property of the applicable pass through trust as provided in the pass through trust agreement.

     The property of each pass through trust for which a series of certificates will be issued will include:

     The rights of a pass through trustee to receive monies payable under equipment notes held for that pass through trustee may be subject to the effect of subordination provisions contained in an intercreditor agreement described in the prospectus supplement for a series of certificates. An intercreditor agreement refers to an agreement among the pass through trustees and, if applicable, a liquidity provider under a liquidity facility, as creditors of the issuers of the equipment notes owned by the pass through trustees. An intercreditor agreement will set forth the terms and conditions upon which payments made under the equipment notes and payments made under any liquidity

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facility will be received, shared and distributed among the several pass through trustees and the liquidity provider. In addition, the intercreditor agreement will set forth agreements among the pass through trustees and the liquidity provider relating to the exercise of remedies under the equipment notes and the indentures.

     Cross-subordination refers to an agreement under which payments on a junior class of equipment notes issued under an indenture are distributed to a pass through trustee that holds a senior class of equipment notes issued under a different indenture on which all required payments were not made. The effect of this distribution mechanism is that holders of certificates of a pass through trust that owns a junior class of equipment notes will not receive payments made on that junior class of equipment notes until certain distributions are made on the certificates of the pass through trust that owns a senior class of equipment notes.

     Equipment notes owned by a pass through trust may be leased aircraft notes, owned aircraft notes or a combination of leased aircraft notes and owned aircraft notes.

     Leased aircraft notes will be issued in connection with the leveraged lease of an aircraft to us. Except as set forth in the applicable prospectus supplement, each leased aircraft will be leased to us under a lease between us, as lessee, and an owner trustee, as lessor. Each owner trustee will issue leased aircraft notes on a non-recourse basis under a separate leased aircraft indenture between it and the applicable loan trustee. The owner trustee will use the proceeds of the sale of the leased aircraft notes to finance or refinance a portion of the purchase price paid or to be paid by the owner trustee for the applicable leased aircraft. The owner trustee will obtain the remainder of the funding for the leased aircraft from an equity contribution from the owner participant that is the beneficiary of the owner trust and, to the extent set forth in the applicable prospectus supplement, additional debt secured by the applicable leased aircraft or other sources. A leased aircraft also may be subject to other financing arrangements.

     Generally, neither the owner trustee nor the owner participant will be personally liable for any principal or interest payable under any leased aircraft indenture or any leased aircraft notes. In some cases, an owner participant may be required to make payments to an owner trustee that are to be used by the owner trustee to pay principal of, and interest on, the equipment notes. If an owner participant is required to make payments to be used by an owner trustee to pay principal of, and interest on, the equipment notes and the owner participant fails to make the payment, we will be required to provide the owner trustee with funds sufficient to make the payment. We will be obligated to make payments or advances under a lease and the related documents sufficient to pay when due all scheduled principal and interest payments on the leased aircraft notes issued to finance the aircraft subject to that lease.

     We will issue owned aircraft notes under separate owned aircraft indentures. Owned aircraft notes will be issued in connection with the financing or refinancing of an aircraft that we own. Owned aircraft notes will be obligations that have recourse to us and the related aircraft. Any owned aircraft may secure additional debt or be subject to other financing arrangements.

     An indenture may provide for the issuance of multiple classes of equipment notes. If an indenture provides for multiple classes of equipment notes, it may also provide for differing priority of payments among the different classes. Equipment notes issued under an indenture may

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be held in more than one pass through trust, and one pass through trust may hold equipment notes issued under more than one indenture. Unless otherwise provided in a prospectus supplement, only equipment notes having the same priority of payment may be held for the same pass through trust.

     Except as set forth in the prospectus supplement for any series of certificates, interest payments on the equipment notes held for a pass through trust will be passed through to the registered holders of certificates of that pass through trust at the annual rate shown on the cover page of the prospectus supplement for the certificates issued by that pass through trust. The certificateholders’ right to receive payments made in respect of the equipment notes is subject to the effect of any cross-subordination provisions described in the prospectus supplement for a series of certificates.

     We refer you to the prospectus supplement that accompanies this prospectus for a description of the specific series of certificates being offered by this prospectus and the applicable prospectus supplement, including:

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     The concept of cross-default mentioned above refers to a situation where a default under one indenture or lease results in a default under other indentures or leases. We currently do not expect any indentures or leases to contain cross-default provisions. The concept of cross-collateralization mentioned above refers to the situation where collateral that secures obligations incurred under one indenture also serves as collateral for obligations under one or more other indentures. We currently do not expect any indentures to be cross-collateralized.

Book-Entry Registration

     General. If specified in the applicable prospectus supplement, the certificates will be subject to the procedures and provisions described below.

     Upon issuance, each series of certificates will be represented by one or more fully registered global certificates. Each global certificate will be deposited with, or on behalf of, The Depository Trust Company, referred to as DTC, and registered in the name of Cede & Co., the nominee of DTC. No purchaser of a certificate will be entitled to receive a physical certificate representing an interest in the global certificates, except as set forth below under “— Physical Certificates.” For convenience, we refer to such purchasers as “certificate owners.” Unless and until physical certificates are issued under the limited circumstances described below, all references in this prospectus and any prospectus supplement to actions by certificateholders will refer to actions taken by DTC upon instructions from DTC participants, and all references to distributions, notices, reports and statements to certificateholders will refer, as the case may be, to distributions, notices, reports and statements to DTC or Cede, as the registered holder of the certificates, or to DTC participants for distribution to certificateholders in accordance with DTC procedures.

     DTC is a limited purpose trust company organized under the laws of the State of New York, a member of the Federal Reserve System, a “clearing corporation” within the meaning of the New York Uniform Commercial Code and “clearing agency” registered pursuant to Section 17A of the Securities Exchange Act of 1934.

     Under the New York Uniform Commercial Code, a “clearing corporation” is defined as:

     A “clearing agency” is an organization established for the execution of trades by transferring funds, assigning deliveries and guaranteeing the performance of the obligations of parties to trades.

     DTC was created to hold securities for its participants and to facilitate the clearance and settlement of securities transactions between DTC participants through electronic book-entry

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changes in the accounts of DTC participants. The ability to execute transactions through book-entry changes in accounts eliminates the need for transfer of physical certificates. DTC is owned by a number of DTC participants and by the New York Stock Exchange, the American Stock Exchange, and the National Association of Securities Dealers. DTC participants include securities brokers and dealers, banks, trust companies and clearing corporations and certain other organizations. Banks, brokers, dealers, trust companies and other entities that clear through or maintain a custodial relationship with a DTC participant, either directly or indirectly, are indirect participants in the DTC system.

     Under the rules, regulations and procedures creating and affecting DTC and its operations, DTC is required to make book-entry transfers of the certificates among DTC participants on whose behalf it acts with respect to the certificates and to receive and transmit distributions of principal, premium, if any, and interest with respect to the certificates. DTC participants and indirect DTC participants with which certificate owners have accounts similarly are required to make book-entry transfers and receive and transmit the payments on behalf of their respective customers. Certificate owners that are not DTC participants or indirect DTC participants but desire to purchase, sell or otherwise transfer ownership of, or other interests in, the certificates may do so only through DTC participants and indirect DTC participants. In addition, certificate owners will receive all distributions of principal, premium, if any, and interest from the pass through trustee through DTC participants or indirect DTC participants, as the case may be.

     Under a book-entry format, certificate owners may experience some delay in their receipt of payments, because payments with respect to the certificates will be forwarded by the pass through trustee to Cede, as nominee for DTC. DTC will forward payments in same-day funds to each DTC participant who is credited with ownership of the certificates in an amount proportionate to the principal amount of that DTC participant’s holdings of beneficial interests in the certificates, as shown on the records of DTC or its nominee. Each such DTC participant will forward payments to its indirect DTC participants in accordance with standing instructions and customary industry practices. DTC participants and indirect DTC participants will be responsible for forwarding distributions to certificate owners for whom they act. Accordingly, although certificate owners will not possess physical certificates, DTC’s rules provide a mechanism by which certificate owners will receive payments on the certificates and will be able to transfer their interests.

     Unless and until physical certificates are issued under the limited circumstances described below, the only physical certificateholder will be Cede, as nominee of DTC. Certificate owners will not be recognized by the pass through trustee as registered owners of certificates under the pass through trust agreement. Certificate owners will be permitted to exercise their rights under the pass through trust agreement only indirectly through DTC. DTC will take any action permitted to be taken by a certificateholder under the pass through trust agreement only at the direction of one or more DTC participants to whose accounts with DTC the certificates are credited. In the event any action requires approval by certificateholders of a certain percentage of the beneficial interests in a pass through trust, DTC will take action only at the direction of and on behalf of DTC participants whose holdings include undivided interests that satisfy the required percentage. DTC may take conflicting actions with respect to other undivided interests to the extent that the actions are taken on behalf of DTC participants whose holdings include those undivided interests. DTC will convey notices and other communications to DTC participants, and DTC participants will convey notices and other communications to indirect DTC participants in accordance with

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arrangements among them. Arrangements among DTC and its direct and indirect participants are subject to any statutory or regulatory requirements as may be in effect from time to time. DTC’s rules applicable to itself and DTC participants are on file with the SEC.

     A certificate owner’s ability to pledge the certificates to persons or entities that do not participate in the DTC system, or otherwise to act with respect to the certificates, may be limited due to the lack of a physical certificate to evidence ownership of the certificates, and because DTC can only act on behalf of DTC participants, who in turn act on behalf of indirect DTC participants.

     Neither we nor the pass through trustee will have any liability for any aspect of the records relating to or payments made on account of beneficial ownership interests in the certificates held by Cede, as nominee for DTC, for maintaining, supervising or reviewing any records relating to the beneficial ownership interests or for the performance by DTC, any DTC participant or any indirect DTC participant of their respective obligations under the rules and procedures governing their obligations.

     The applicable prospectus supplement will specify any additional book-entry registration procedures applicable to certificates denominated in a currency other than U.S. dollars.

     Same-Day Settlement and Payment. As long as the certificates are registered in the name of DTC or its nominee, we will make all payments to the loan trustee under any lease or any owned aircraft indenture in immediately available funds. The pass through trustee will pass through to DTC in immediately available funds all payments received from us, including the final distribution of principal with respect to the certificates of any pass through trust.

     Any certificates registered in the name of DTC or its nominee will trade in DTC’s Same-Day Funds Settlement System until maturity. DTC will require secondary market trading activity in the certificates to settle in immediately available funds. We cannot give any assurance as to the effect, if any, of settlement in same-day funds on trading activity in the certificates.

     Physical Certificates. Physical certificates will be issued in paper form to certificateholders or their nominees, rather than to DTC or its nominee, only if:

     Upon the occurrence of any of the events described in the three subparagraphs above, the applicable pass through trustee will notify all certificate owners through DTC participants of the availability of physical certificates. Upon surrender by DTC of the global certificates and receipt

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of instructions for re-registration, the pass through trustee will reissue the certificates as physical certificates to certificate owners.

     After physical certificates are issued, the pass through trustee or a paying agent will make distributions of principal, premium, if any, and interest with respect to certificates directly to holders in whose names the physical certificates were registered at the close of business on the applicable record date. Except for the final payment to be made with respect to a certificate, the pass through trustee or a paying agent will make distributions by check mailed to the addresses of the registered holders as they appear on the register maintained by the pass through trustee. The pass through trustee or a paying agent will make the final payment with respect to any pass through certificate only upon presentation and surrender of the applicable pass through certificate at the office or agency specified in the notice of final distribution to certificateholders.

     Physical certificates will be freely transferable and exchangeable at the office of the pass through trustee upon compliance with the requirements set forth in the pass through trust agreement. Neither the pass through trustee nor any transfer or exchange agent will impose a service charge for any registration of transfer or exchange. However, the pass through trustee or transfer or exchange agent will require payment of a sum sufficient to cover any tax or other governmental charge attributable to a transfer or exchange.

Payments and Distributions

     Subject to the effect of any cross-subordination provisions set forth in the prospectus supplement for a series of certificates:

     If we elect or are required to redeem equipment notes relating to one or more aircraft prior to their scheduled maturity date, payments of principal, premium (if any) and interest received by the pass through trustee as a result of the early redemption will be distributed on a special distribution date determined as described in the applicable prospectus supplement. Payments received by the pass through trustee following a default under the equipment notes held for a pass through trust will also be distributed on a special distribution date determined in the same way. However, if following such a default the pass through trustee receives any scheduled payments on equipment notes on a regular distribution date or within five days thereafter, the pass through trustee will distribute those payments on the date they are received. In addition, if following a

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default under equipment notes the pass through trustee receives payments on the equipment notes on a regular distribution date by making a drawing under any liquidity facility, as described in the applicable prospectus supplement, those payments will be distributed to certificateholders on the regular distribution date. The pass through trustee will mail notice to the certificateholders of record of the applicable pass through trust stating the anticipated special distribution date.

Pool Factors

     Unless otherwise described in the applicable prospectus supplement, the “pool balance” for each pass through trust or for the certificates issued by any pass through trust indicates, as of any date, the portion of the original aggregate face amount of the certificates issued by that pass through trust that has not been distributed to certificateholders (excluding any payments of interest or premium). The pool balance for each pass through trust as of any distribution date will be computed after giving effect to any distribution to certificateholders to be made on that date.

     Unless otherwise described in the applicable prospectus supplement, the “pool factor” for a pass through trust as of any distribution date for that trust is the quotient (rounded to the seventh decimal place) computed by dividing (a) the pool balance by (b) the original aggregate face amount of the certificates issued by that pass through trust. The pool factor for a pass through trust as of any distribution date will be computed after giving effect to the payment of principal, if any, on the equipment notes held for that pass through trust and distribution to certificateholders of the payment of principal to be made on that date. Each pass through trust will have a separate pool factor.

     The pool factor for a pass through trust initially will be 1.0000000. The pool factor for a pass through trust will decline as described in this prospectus and the related prospectus supplement to reflect reductions in the pool balance of that pass through trust. As of any distribution date for a pass through trust, a certificate will represent a share of the pool balance of that pass through trust equal to the product obtained by multiplying the original face amount of the certificate by the pool factor for the pass through trust that issued such certificate. The pool factor and pool balance of each past through trust will be mailed to the certificateholders of the pass through trust on each distribution date.

     The pool factor for each pass through trust will decline in proportion to the scheduled repayments of principal on the equipment notes held by that pass through trust, unless there is an early redemption or purchase of equipment notes held by a pass through trust or if a default occurs in the repayment of equipment notes held by a pass through trust. In the event of a redemption, purchase or default, the pool factor and the pool balance of each pass through trust affected by the redemption, purchase or default will be recomputed, and a notice will be mailed to the certificateholders of the pass through trust.

Reports to Certificateholders

     The pass through trustee will include with each distribution of a payment to certificateholders a statement setting forth the following information:

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     As long as the certificates are registered in the name of DTC or its nominee, on the record date prior to each distribution date, the pass through trustee will request from DTC a securities position listing setting forth the names of all DTC participants reflected on DTC’s books as holding interests in the certificates on that record date. On each distribution date, the applicable pass through trustee will mail to each DTC participant holding certificates the statement described above and will make available additional copies as requested by the DTC participants for forwarding to certificate owners.

     After the end of each calendar year, each pass through trustee will prepare a report for each person that was a holder of one or more of its pass through certificates at any time during the preceding calendar year. This report will contain the sum of the amount of distributions allocable to principal, premium and interest with respect to that pass through trust for the preceding calendar year or, if the person was a holder of a pass through certificate during only a portion of the preceding calendar year, for the applicable portion of the preceding calendar year. In addition, each pass through trustee will prepare for each person that was a holder of one or more of its pass through certificates at any time during the preceding calendar year any other information that is readily available to the pass through trustee and which a certificateholder reasonably requests as necessary for the purpose of preparing its federal income tax returns. The reports and other items described in this section will be prepared on the basis of information supplied to the pass through trustee by DTC participants and will be delivered by the pass through trustee to DTC participants to be available for forwarding by DTC participants to certificate owners in the manner described above.

     If the certificates of a pass through trust are issued in the form of physical certificates, the pass through trustee of that pass through trust will prepare and deliver the information described above to each record holder of a pass through certificate issued by that pass through trust as the name and period of ownership of the holder appears on the records of the registrar of the certificates.

Voting of Equipment Notes

     A pass through trustee has the right to vote and give consents and waivers with respect to the equipment notes held by that pass through trust. However, the pass through trustee’s right to vote and give consents or waivers may be restricted or may be exercisable by another person in accordance with the terms of an intercreditor agreement, as described in the applicable prospectus supplement. The pass through trust agreement will set forth:

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     If the holders of certificates are entitled to the benefits of a liquidity facility, and the liquidity facility is used to make any payments to certificateholders, the provider of the liquidity facility may be entitled to exercise rights to vote or give consents and waivers with respect to the equipment notes held for the pass through trust that issued the certificates, as described in the applicable prospectus supplement.

Events of Default and Certain Rights Upon an Event of Default

     The prospectus supplement will specify the events of default that can occur under the pass through trust agreement and under the indentures relating to the equipment notes held for the related pass through trust. In the case of a leased aircraft indenture, an indenture default will include events of default under the related lease. In the case of any equipment notes that are supported by a liquidity facility, a default may include events of default under that liquidity facility.

     Unless otherwise provided in a prospectus supplement, all of the equipment notes issued under the same indenture will relate to a specific aircraft and there will be no cross-collateralization or cross-default provisions in the indentures. As a result, events resulting in a default under any particular indenture will not necessarily result in an a default under any other indenture. If a default occurs in fewer than all of the indentures, payments of principal and interest on the equipment notes issued under the indentures with respect to which a default has not occurred will continue to be made as originally scheduled.

     As described below under “— Cross-Subordination Issues,” a prospectus supplement may describe the terms of any cross-subordination provisions among certificateholders of separate pass through trusts. If cross-subordination is provided, payments made pursuant to an indenture under which a default has not occurred may be distributed first to the holders of the certificates issued under the pass through trust which holds the most senior equipment notes issued under all of the indentures.

     The ability of the applicable owner trustee or owner participant under a leased aircraft indenture to cure a default under the indenture, including a default that results from the occurrence of a default under the related lease, will be described in the prospectus supplement. Unless otherwise provided in a prospectus supplement, with respect to any pass through certificates or equipment notes entitled to the benefits of a liquidity facility, a drawing under the liquidity facility for the purpose of making a payment of interest as a result of our failure to have made a corresponding payment will not cure a default related to our failure.

     The prospectus supplement related to a series of pass through certificates will describe the circumstances under which the pass through trustee of the related pass through trust may vote some or all of the equipment notes held in the pass through trust. The prospectus supplement also will set forth the percentage of certificateholders of the pass through trust entitled to direct the pass

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through trustee to take any action with respect to the equipment notes. If the equipment notes outstanding under an indenture are held by more than one pass through trust, then the ability of the certificateholders issued with respect to any one pass through trust to cause the loan trustee with respect to any equipment notes held in the pass through trust to accelerate the equipment notes under the applicable indenture or to direct the exercise of remedies by the loan trustee under the applicable indenture will depend, in part, upon the proportion of the aggregate principal amount of the equipment notes outstanding under that indenture and held in that pass through trust to the aggregate principal amount of all equipment notes outstanding under that indenture.

     In addition, if cross-subordination provisions are applicable to any series of certificates, then the ability of the certificateholders of any one pass through trust holding equipment notes issued under an indenture to cause the loan trustee with respect to any equipment notes held in that pass through trust to accelerate the equipment notes under that indenture or to direct the exercise of remedies by the loan trustee under that indenture will depend, in part, upon the class of equipment notes held in the pass through trust. If the equipment notes outstanding under an indenture are held by more than one pass through trust, then each pass through trust will hold equipment notes with different terms from the equipment notes held in the other pass through trusts and therefore the certificateholders of each pass through trust may have divergent or conflicting interests from those of the certificateholders of the other pass through trusts holding equipment notes issued under the same indenture. In addition, so long as the same institution acts as pass through trustee of each pass through trust, in the absence of instructions from the certificateholders of any pass through trust, the pass through trustee for the pass through trust could for the same reason be faced with a potential conflict of interest upon a default under an indenture. In that event, the pass through trustee has indicated that it would resign as pass through trustee of one or all the pass through trusts, and a successor trustee would be appointed in accordance with the terms of the Basic Agreement.

     The prospectus supplement for a series of certificates will specify whether and under what circumstances the pass through trustee may sell for cash to any person all or part of the equipment notes held in the related pass through trust. Any proceeds received by the pass through trustee upon a sale will be deposited in an account established by the pass through trustee for the benefit of the certificateholders of the pass through trust for the deposit of the special payments and will be distributed to the certificateholders of the pass through trust on a special distribution date.

     The market for equipment notes in default may be very limited, and we cannot assure you that they could be sold for a reasonable price. Furthermore, so long as the same institution acts as pass through trustee of multiple pass through trusts, it may be faced with a conflict in deciding from which pass through trust to sell equipment notes to available buyers. If the pass through trustee sells any equipment notes with respect to which a default under an indenture exists for less than their outstanding principal amount, the certificateholders of that pass through trust will receive a smaller amount of principal distributions than anticipated and will not have any claim for the shortfall against us, any owner trustee, owner participant or the pass through trustee. Furthermore, neither the pass through trustee nor the certificateholders of that pass through trust could take any action with respect to any remaining equipment notes held in that pass through trust so long as no default under an indenture exists.

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     Any amount, other than scheduled payments received on a regular distribution date, distributed to the pass through trustee of any pass through trust by the loan trustee under any indenture on account of the equipment notes held in that pass through trust following a default under such indenture will be deposited in the special payments account for that pass through trust and will be distributed to the certificateholders of that pass through trust on a special distribution date. In addition, if a prospectus supplement provides that the applicable owner trustee may, under circumstances specified in the prospectus supplement, redeem or purchase the outstanding equipment notes issued under the applicable indenture, the price paid by the owner trustee to the pass through trustee of any pass through trust for the equipment notes issued under that indenture and held in that pass through trust will be deposited in the special payments account for the pass through trust and will be distributed to the certificateholders of the pass through trust on a special distribution date.

     Any funds representing payments received with respect to any equipment notes in default held in a pass through trust, or the proceeds from the sale by the pass through trustee of any of those equipment notes, held by the pass through trustee in the special payments account for that pass through trust will, to the extent practicable, be invested and reinvested by the pass through trustee in permitted investments pending the distribution of the funds on a special distribution date. Permitted investments will be specified in the related prospectus supplement.

     The Basic Agreement provides that the pass through trustee of each pass through trust will give to the certificateholders of that pass through trust notice of all uncured or unwaived defaults known to it with respect to that pass through trust. The Basic Agreement requires the pass through trustee to provide the notice of default within 90 days after the occurrence of the default. However, except in the case of default in the payment of principal, premium, if any, or interest on any of the equipment notes held for a pass through trust, the pass through trustee will be protected in withholding a notice of default if it in good faith determines that withholding the notice is in the interest of the certificateholders of such pass through trust. The term “default” as used in this paragraph means only the occurrence of a default under an indenture with respect to equipment notes held in a pass through trust as described above, except that in determining whether any default under an indenture has occurred, any related grace period or notice will be disregarded.

     The Basic Agreement requires the pass through trustee to act with a specified standard of care while a default is continuing under an indenture. In addition, the Basic Agreement contains a provision entitling the pass through trustee to require reasonable security or indemnification by the certificateholders of the pass through trust before proceeding to exercise any right or power under the Basic Agreement at the request of those certificateholders.

     The prospectus supplement for a series of certificates will specify the percentage of certificateholders entitled to waive, or to instruct the pass through trustee to waive, any past default with respect to the related pass through trust and its consequences. The prospectus supplement for a series of certificates also will specify the percentage of certificateholders entitled to waive, or to instruct the pass through trustee or the loan trustee to waive, any past default under an indenture.

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Merger, Consolidation and Transfer of Assets

     We will be prohibited from consolidating with or merging into any other entity or transferring substantially all of our assets as an entirety to any other entity unless the surviving, successor or transferee entity:

     In addition, we will be required to deliver a certificate and an opinion or opinions of counsel indicating that the transaction, in effect, complies with these conditions.

Modifications of the Basic Agreement

     The Basic Agreement contains provisions permitting us and the pass through trustee of each pass through trust to enter into a supplemental trust agreement, without the consent of the holders of any of the certificates issued by such pass through trust, in order to do the following, among other things:

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     No pass through trust supplement may be made that will adversely affect the status of any pass through trust as a grantor trust for U.S. federal income tax purposes.

     The Basic Agreement also contains provisions permitting us and the pass through trustee of each pass through trust, with the consent of a majority in interest of the certificateholders of the pass through trust, to execute supplemental trust agreements adding any provisions to or changing or eliminating any of the provisions of the Basic Agreement, to the extent relating to that pass through trust, and the applicable pass through trust supplement, or modifying the rights of the certificateholders, except that no supplement may, without the consent of each affected certificateholder:

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Modification of Indenture and Related Agreements

     The prospectus supplement will specify the pass through trustee’s obligations if a pass through trustee, as the holder of any equipment notes held for a pass through trust, receives a request for its consent to any amendment, modification or waiver under the indenture under which the equipment notes were issued, under the lease relating to the aircraft leased by us that was financed with the proceeds of the equipment notes or under any liquidity facility.

Cross-Subordination Issues

     The equipment notes issued under an indenture may be held in more than one pass through trust, and one pass through trust may hold equipment notes issued under more than one indenture. Unless otherwise provided in a prospectus supplement, only equipment notes having the same priority for distributions under the applicable indenture may be held in the same pass through trust. In that event, payments made on account of a subordinate class of certificates issued under a prospectus supplement may be subordinated, under circumstances described in the prospectus supplement, to the prior payment of all amounts owing to certificateholders of a pass through trust which holds senior equipment notes issued under the applicable indentures. The prospectus supplement related to an issuance of certificates will describe the “cross-subordination” provisions and any related terms, including the percentage of certificateholders under any pass through trust which are permitted to:

Termination of the Pass Through Trusts

     Our obligations and those of the pass through trustee with respect to a pass through trust will terminate upon the distribution to certificateholders of the pass through trust of all amounts required to be distributed to them pursuant to the applicable pass through trust agreement and the disposition of all property held in the pass through trust. In no event will any pass through trust continue beyond 110 years following the date of the execution of the applicable pass through trust supplement, or any other final expiration date as may be specified in the pass through trust supplement. The pass through trustee will send to each certificateholder of record of the pass through trust notice of the termination of the pass through trust, the amount of the proposed final payment and the proposed date for the distribution of the final payment for the pass through trust. The final distribution to any certificateholder of the pass through trust will be made only upon surrender of that certificateholder’s certificates at the office or agency of the pass through trustee specified in the notice of termination.

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Delayed Purchase of Equipment Notes

     On the issuance date of any certificates, if all of the proceeds from the sale of the certificates are not used to purchase the equipment notes contemplated to be held in the related pass through trust, the equipment notes may be purchased by the pass through trustee at any time on or prior to the date specified in the applicable prospectus supplement. In that event, the proceeds from the sale of the certificates not used to purchase equipment notes will be held under an arrangement described in the applicable prospectus supplement pending the purchase of equipment notes. The arrangements with respect to the payment of interest on funds so held will be described in the applicable prospectus supplement. If any proceeds are not used to purchase equipment notes by the date specified in the applicable prospectus supplement, the proceeds will be returned to the certificateholders.

Liquidity Facility

     The related prospectus supplement may provide that one or more payments of interest on the certificates of one or more series will be supported by a liquidity facility issued by an institution identified in the related prospectus supplement. The provider of the liquidity facility may have a claim on money and property belonging to a pass through trust that is senior to the certificateholders’ as specified in the related prospectus supplement.

The Pass Through Trustee

     Unless otherwise provided in the prospectus supplement for any series of certificates, the pass through trustee for each series of certificates will be Wilmington Trust Company. With certain exceptions, the pass through trustee makes no representations as to the validity or sufficiency of the Basic Agreement, the pass through trust supplements, the certificates, the equipment notes, the indentures, the leases or other related documents. The pass through trustee will not be liable with respect to any series of certificates for any action taken or omitted to be taken by it in good faith in accordance with the direction of the holders of a majority in principal amount of outstanding certificates of that series issued under the Basic Agreement. Subject to those provisions, the pass through trustee will be under no obligation to exercise any of its rights or powers under the Basic Agreement at the request of any holders of certificates issued under that agreement unless they will have offered to the pass through trustee indemnity satisfactory to it. The Basic Agreement provides that the pass through trustee in its individual or any other capacity may acquire and hold certificates and, subject to certain conditions, may otherwise deal with us and, with respect to the leased aircraft, with any owner trustee with the same rights it would have if it were not the pass through trustee.

     The pass through trustee may resign with respect to any or all of the pass through trusts at any time, in which event we will be obligated to appoint a successor trustee. If the pass through trustee ceases to be eligible to continue as pass through trustee with respect to a pass through trust or becomes incapable of acting as pass through trustee or becomes insolvent, we may remove the pass through trustee, or any certificateholder of the pass through trust for at least six months may, on behalf of himself and all others similarly situated, petition any court of competent jurisdiction for the removal of the pass through trustee and the appointment of a successor trustee. Any resignation or removal of the pass through trustee with respect to a pass through trust and

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appointment of a successor trustee for the pass through trust does not become effective until acceptance of the appointment by the successor trustee. Pursuant to the resignation and successor trustee provisions, it is possible that a different trustee could be appointed to act as the successor trustee with respect to each pass through trust. All references in this prospectus to the pass through trustee should be read to take into account the possibility that the pass through trusts could have different successor trustees in the event of a resignation or removal.

     The Basic Agreement provides that we will pay the pass through trustee’s fees and expenses and indemnify the pass through trustee against certain liabilities.

DESCRIPTION OF THE EQUIPMENT NOTES

     The statements made under this caption are summaries, and we refer you to the entire prospectus and detailed information appearing in the applicable prospectus supplement. Where no distinction is made between the leased aircraft notes and the owned aircraft notes or between their respective indentures, those statements refer to any equipment notes and any indenture.

     To the extent that any provision in any prospectus supplement is inconsistent with any provision in this summary, the provision of the prospectus supplement will control.

General

     The equipment notes will be issued under indentures. Equipment notes secured by an aircraft that is leased to us will be issued under an indenture between an owner trustee and a loan trustee. Equipment notes secured by an aircraft that is owned by us will be issued under an indenture between a loan trustee and us.

     The leased aircraft notes will be non-recourse obligations of the applicable owner trustee. All of the leased aircraft notes issued under the same indenture will relate to and will be secured by one or more specific aircraft leased to us. Unless otherwise specified in the applicable prospectus supplement, leased aircraft notes will not be secured by any other aircraft. We will be the issuer of owned aircraft notes. The owned aircraft notes will be our direct recourse obligations. All of the owned aircraft notes issued under the same indenture will relate to, and will be secured by, one or more specific aircraft that we own. Unless otherwise specified in the applicable prospectus supplement, the owned aircraft notes will not be secured by any other aircraft.

Principal and Interest Payments

     Interest received by the pass through trustee on the equipment notes held in a pass through trust will be passed through to the certificateholders of that pass through trust on the dates and at the annual rate set forth in the applicable prospectus supplement until the final distribution for that pass through trust. Principal payments received by the pass through trustee on the equipment notes held in a pass through trust will be passed through to the certificateholders of that pass through trust in scheduled amounts on the dates set forth in the applicable prospectus supplement until the final distribution date for that pass through trust.

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     If any date scheduled for any payment of principal, premium, if any, or interest with respect to the equipment notes is not a business day, the payment will be made on the next succeeding business day without any additional interest.

Redemption

     The applicable prospectus supplement will describe the circumstances, whether voluntary or involuntary, under which the equipment notes may be redeemed or purchased prior to their stated maturity date, in whole or in part. The prospectus supplement will also describe the premium, if any, applicable upon redemptions or purchases and other terms applying to the redemptions or purchases of the equipment notes.

Security

     The leased aircraft notes will be secured by:

     Under the terms of each lease, our obligations in respect of each leased aircraft will be those of a lessee under a “net lease.” Accordingly, we will be obligated, among other things and at our expense, to cause each leased aircraft to be duly registered, to pay all costs of operating the aircraft and to maintain, service, repair and overhaul the aircraft or cause it to be maintained, serviced, repaired and overhauled. With respect to the leased aircraft, the assignment by the related owner trustee to the related loan trustee of its rights under the related lease will exclude, among other things:

     The owned aircraft notes will be secured by a mortgage granted to the related loan trustee of all of our right, title and interest in and to the owned aircraft. Under the terms of each owned

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aircraft indenture, we will be obligated, among other things and at our expense, to cause each owned aircraft to be duly registered, to pay all costs of operating the aircraft and to maintain, service, repair and overhaul the aircraft or cause it to be maintained, serviced, repaired and overhauled.

     We will be required, except under certain circumstances, to keep each aircraft registered under the Transportation Code, and to record the indenture and the lease, if applicable, among other documents, with respect to each aircraft under the Transportation Code. Recordation of the indenture, the lease, if applicable, and other documents with respect to each aircraft will give the related loan trustee a perfected security interest in the related aircraft whenever it is located in the United States or any of its territories and possessions. The Convention on the International Recognition of Rights in Aircraft, referred to as the “Convention,” provides that this security interest will also be recognized, with certain limited exceptions, in those jurisdictions that have ratified or adhere to the Convention.

     We will have the right, subject to certain conditions, at our own expense to register each aircraft in countries other than the United States. Each aircraft may also be operated by us or under lease, sublease or interchange arrangements in countries that are not parties to the Convention. The extent to which the related loan trustee’s security interest would be recognized in an aircraft located in a country that is not a party to the Convention, and the extent to which the security interest would be recognized in a jurisdiction adhering to the Convention if the aircraft is registered in a jurisdiction not a party to the Convention, is uncertain. Moreover, in the case of a default under an indenture, the ability of the related loan trustee to realize upon its security interest in an aircraft could be adversely affected as a legal or practical matter if the aircraft were registered or located outside the United States.

     Unless otherwise specified in the applicable prospectus supplement, the equipment notes will not be cross-collateralized. Consequently, the equipment notes issued in respect of any one aircraft will not be secured by any other aircraft. Unless and until a default under an indenture with respect to a leased aircraft has occurred and is continuing, the related loan trustee may exercise only limited rights of the related owner trustee under the related lease. The loan trustee will invest and reinvest funds, if any, held by it from time to time under an indenture. The loan trustee will, at our direction, invest and reinvest funds in certain investments described in the applicable indenture. We will not be entitled to direct the loan trustee to invest and reinvest funds with respect to a leased aircraft in the case of a default under the applicable lease or, with respect to an owned aircraft, in the case of a default under the applicable indenture. We will pay the net amount of any loss resulting from these investments.

     In the case of Chapter 11 bankruptcy proceedings involving a holder of “equipment” (defined as described below), Section 1110 of the U.S. Bankruptcy Code provides special rights to lessors, conditional vendors and holders of security interests with respect to such equipment. Under Section 1110, the right of such financing parties to take possession of such equipment in compliance with the provisions of a lease, conditional sale contract or security agreement is not affected by any provision of the U.S. Bankruptcy Code or any power of the bankruptcy court. Ordinarily, such right would be limited by the “automatic stay” under the Bankruptcy Code. Such right to take possession may not be exercised for 60 days following the date of commencement of the reorganization proceedings. Thereafter, such right to take possession may be exercised during

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such proceedings unless, within the 60-day period or any longer period consented to by the relevant parties, the debtor agrees to perform its obligations that become due on or after that date and cures all defaults on a timely basis. Defaults resulting solely from the financial condition, bankruptcy, insolvency or reorganization of the debtor need not be cured.

     “Equipment” is defined in Section 1110 of the U.S. Bankruptcy Code, in part, as an aircraft, aircraft engine, propeller, appliance, or spare part (as defined in Section 40102 of Title 49 of the U.S. Code) that is subject to a security interest granted by, leased to, or conditionally sold to a debtor that, at the time such transaction is entered into, holds an air carrier operating certificate issued pursuant to chapter 447 of title 49 of the U.S. Code for aircraft capable of carrying 10 or more individuals or 6,000 pounds of more of cargo (subject to certain limitations in the case of equipment first placed in service on or prior to October 22, 1994).

     In connection with any issuance of certificates under this prospectus and the applicable prospectus supplement, it will be a condition to the pass through trustee’s obligation to purchase equipment notes with respect to each aircraft that our outside counsel provide its opinion (which may assume that we hold, at the time of the lease or mortgage, as the case may be, an air carrier operating certificate issued pursuant to chapter 447 of title 49 of the U.S. Code for aircraft capable of carrying 10 or more individuals or 6,000 pounds or more of cargo) to the Pass Through Trustee that:

     The opinion will not address the possible replacement of an aircraft after an “Event of Loss,” as defined in the applicable indenture, in the future.

Ranking of Equipment Notes

     Some of the equipment notes related to one or more aircraft, as described in the related prospectus supplement, may be subordinated and junior in right of payment to other equipment notes related to the same aircraft. The terms of the subordination, if any, will be described in the related prospectus supplement.

Payments and Limitation of Liability

     We will lease each leased aircraft from an owner trustee for a term commencing on the delivery date of the aircraft to the owner trustee and expiring on a date no earlier than the latest maturity date of the related leased aircraft notes, unless previously terminated as permitted by the terms of the related lease. We will make basic rent and other payments under each lease to an owner trustee, as lessor. The owner trustee will assign these payments under the applicable indenture to the related loan trustee to provide the funds necessary to pay principal of, premium, if

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any, and interest due from the owner trustee on the leased aircraft notes issued under the indenture. Each lease will provide that under no circumstances will our rent payments be less than the scheduled payments on the related leased aircraft notes. The balance of any basic rent payment under each lease, after payment of amounts due on the leased aircraft notes issued under the indenture corresponding to the lease, will be paid over to the applicable owner trustee. Our obligation to pay rent and to cause other payments to be made under each lease will be our direct obligation. Except in circumstances in which we purchase a leased aircraft and assume the related leased aircraft notes, the leased aircraft notes will not be our direct obligation. None of the owner trustees, the owner participants or the loan trustees will be personally liable to any holder of leased aircraft notes for amounts payable under the leased aircraft notes. Except as provided in the indentures relating to the leased aircraft notes, no owner trustee or loan trustee will be liable for or incur any liability under the indentures. Except in the circumstances described above, all amounts payable under any leased aircraft notes, other than payments made in connection with an optional redemption or purchase by the related owner trustee or the related owner participant, will be made only from:

     With respect to the leased aircraft notes, except as otherwise provided in the applicable indenture, no owner trustee will be personally liable for any amount payable or for any statements, representations, warranties, agreements or obligations under any indenture or under any leased aircraft notes. None of the owner participants will have any duty or responsibility under the leased aircraft indentures or under the leased aircraft notes to the related loan trustee or to any holder of any leased aircraft note.

     Our obligations under each owned aircraft indenture and under the owned aircraft notes will be our direct obligations.

Defeasance of the Indentures and the Equipment Notes in Certain Circumstances

     Unless otherwise specified in the applicable prospectus supplement, an indenture may provide that the obligations of the related loan trustee, the related owner trustee or us, as the case may be, under that indenture will be deemed to have been discharged and paid in full on the 91st day after the date that money or certain United States government securities, in an aggregate amount sufficient to pay when due (including as a consequence of redemption in respect of which notice is given on or prior to the date of the deposit) principal, premium, if any, and interest on all equipment notes issued under that indenture, are irrevocably deposited with the related loan trustee. The discharge may occur only if, among other things, there has been published by the IRS a ruling to the effect that holders of the equipment notes will not recognize income, gain or loss for federal income tax purposes as a result of the deposit, defeasance and discharge and will be subject to federal income tax on the same amount and in the same manner and at the same time as would have been the case if the deposit, defeasance and discharge had not occurred.

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     Upon defeasance of the equipment notes, or upon payment in full of the principal of, premium, if any, and interest on all equipment notes issued under any indenture on the applicable maturity date, or upon deposit with the applicable loan trustee of sufficient money no earlier than one year prior to the date of maturity, the holders of the equipment notes will have no beneficial interest in or other rights with respect to the related aircraft or other assets subject to the lien of the indenture and the lien will terminate.

Assumption of Obligations by Southwest

     Unless otherwise specified in the applicable prospectus supplement, upon our purchase of any leased aircraft prior to the end of the applicable term, we may assume on a full recourse basis all of the obligations of the owner trustee, other than its obligations in its individual capacity, under the indenture and the leased aircraft notes relating to that lease. If we assume leased aircraft notes, provisions relating to maintenance, possession and use of the related aircraft, liens and insurance will be incorporated into the indenture. If we assume leased aircraft notes in connection with our purchase of a leased aircraft, leased aircraft notes issued under the indenture will not be redeemed and will continue to be secured by the aircraft.

Liquidity Facility

     The related prospectus supplement may provide that one or more payments of interest on the related equipment notes of one or more series will be supported by a liquidity facility issued by an institution identified in the related prospectus supplement. Unless otherwise provided in the related prospectus supplement, the provider of the liquidity facility will have a claim upon the assets securing the equipment notes senior to the claim of the pass through trustee, as owner of the equipment notes.

Intercreditor Issues

     Equipment notes may be issued in different classes, which means that the equipment notes may have different payment priorities even though they are issued by the same borrower and relate to the same aircraft. If multiple classes of equipment notes are issued, the related prospectus supplement will describe the priority of distributions among the equipment notes, any liquidity facilities, the ability of any class to exercise and/or enforce any or all remedies with respect to the related aircraft, and, if the equipment notes are leased aircraft notes, the related lease, and certain other intercreditor terms and provisions.

CERTAIN UNITED STATES FEDERAL INCOME TAX CONSEQUENCES

General

     Unless otherwise indicated in the applicable prospectus supplement, the following summary describes all material generally applicable U.S. federal income tax consequences to certificateholders of the purchase, ownership and disposition of the certificates offered by this prospectus, and in the opinion of Vinson & Elkins L.L.P., our special tax counsel, is accurate in all material respects with respect to the matters discussed in this prospectus. Except as otherwise specified, the summary is addressed to beneficial owners of certificates that are citizens or residents of the United States, corporations, partnerships or other entities created or organized in or under the

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laws of the United States or any state therein, or estates the income of which is subject to U.S. federal income taxation regardless of its source, or trusts that meet the following two tests: (a) a U.S. court is able to exercise primary supervision over the administration of the trust and (b) one or more U.S. fiduciaries have the authority to control all substantial decisions of the trust that will hold the certificates as capital assets.

     This summary does not address the tax treatment of U.S. certificateholders that may be subject to special tax rules, such as banks, insurance companies, dealers in securities or commodities, holders subject to the mark-to-market rules, tax-exempt entities, holders that will hold certificates as part of a straddle or holders that have a “functional currency” other than the U.S. dollar, nor, except as specifically indicated, does it address the tax treatment of U.S. certificateholders that do not acquire certificates at the public offering price as part of the initial offering. The summary is not a comprehensive description of all of the tax considerations that may be relevant to a decision to purchase certificates. This summary does not describe any tax consequences arising under the laws of any state, locality or taxing jurisdiction other than the United States, nor does it describe any estate or gift tax consequences.

     The summary is based upon the tax laws and practice of the United States as in effect on the date of this prospectus, as well as judicial and administrative interpretations, in final or proposed form, available on or before that date. All of the foregoing are subject to change, which change could apply retroactively, and could alter the tax consequences discussed below. We have not sought any ruling from the IRS with respect to the tax consequences discussed below, and we cannot assure you that the IRS will not take contrary positions. The pass through trusts are not indemnified for any federal income taxes that may be imposed upon them, and the imposition of any such taxes on a pass through trust could result in a reduction in the amounts available for distribution to the certificateholders of that pass through trust. Prospective investors should consult their own tax advisors with respect to the federal, state, local and foreign tax consequences to them of the purchase, ownership and disposition of the certificates.

Tax Status of the Pass Through Trusts

     In the opinion of our special tax counsel, each pass through trust will be classified as a grantor trust and not as an association taxable as a corporation for U.S. federal income tax purposes.

Taxation of Certificateholders Generally

     A U.S. certificateholder will be treated as owning its pro rata undivided interest in each of the equipment notes and any other property held by the related pass through trust. Accordingly, each U.S. certificateholder’s share of interest paid on the equipment notes will be taxable as ordinary income, as it is paid or accrued, in accordance with such U.S. certificateholder’s method of accounting for U.S. federal income tax purposes, and a U.S. certificateholder’s share of any premium paid on redemption of an equipment note will be treated as capital gain. If a pass through trust is supported by a liquidity facility, any amounts received by the pass through trust under the liquidity facility with respect to unpaid interest will be treated for U.S. federal income tax purposes as having the same characteristics as the payments they replace. If we assume an owner trust’s obligations under leased aircraft notes, the assumption would be treated for federal income tax

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purposes as a taxable exchange of the leased aircraft notes, resulting in recognition of gain or loss by the U.S. certificateholder.

     Each U.S. certificateholder will be entitled to deduct, consistent with its method of accounting, its pro rata share of fees and expenses paid or incurred by the corresponding pass through trust as provided in Section 162 or 212 of the Internal Revenue Code of 1986, as amended, referred to herein as the “Code.” Certain fees and expenses, including fees paid to the pass through trustee and the provider of the liquidity facility, if applicable, will be paid by parties other than the certificateholders. These fees and expenses could be treated as constructively received by the pass through trust, in which event a U.S. certificateholder will be required to include in income and will be entitled to deduct its pro rata share of the fees and expenses. If a U.S. certificateholder is an individual, estate or trust, the deduction for the certificateholder’s share of fees or expenses will be allowed only to the extent that all of the certificateholder’s miscellaneous itemized deductions, including the certificateholder’s share of fees and expenses, exceed 2% of the certificateholder’s adjusted gross income. In addition, in the case of U.S. certificateholders who are individuals, certain otherwise allowable itemized deductions will be subject generally to additional limitations on itemized deductions under applicable provisions of the Code.

Effect of Subordination of Certificateholders of Subordinated Trusts

     If any pass through trust is subordinated in right of payment to any other pass through trust and the subordinated trust receives less than the full amount of the interest, principal or premium paid with respect to the equipment notes held by it because of the subordination of such pass through trust, the certificateholders of the subordinated trust would probably be treated for federal income tax purposes as if they had:

     Under this analysis:

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     These results should not significantly affect the inclusion of income for certificateholders on the accrual method of accounting, but could accelerate inclusion of income to certificateholders on the cash method of accounting by, in effect, placing them on the accrual method.

Original Issue Discount

     The equipment notes may be issued with original issue discount, referred to as OID. The prospectus supplement will state whether any equipment notes to be held by the related pass through trust will be issued with OID. Generally, a holder of a debt instrument issued with OID that is not negligible must include the OID in income for federal income tax purposes as it accrues, in advance of the receipt of the cash attributable to such income, under a method that takes into account the compounding of interest.

Sale or Other Disposition of the Certificates

     Upon the sale, exchange or other disposition of a certificate, a U.S. certificateholder generally will recognize capital gain or loss equal to the difference between the amount realized on the disposition, other than any amount attributable to accrued interest which will be taxable as ordinary income, and the U.S. certificateholder’s adjusted tax basis in the related equipment notes and any other property held by the corresponding pass through trust. Any gain or loss will be long-term capital gain or loss to the extent attributable to property held by the pass through trust for more than one year. In the case of individuals, estates, and trusts, the maximum rate of tax on net long-term capital gains is currently 15%. Notwithstanding the foregoing, if the pass through trust is classified as a partnership, gain or loss with respect to an interest in a pass through trust will be calculated and characterized by reference to the U.S. certificateholder’s adjusted tax basis and holding period for its interest in the pass through trust.

Foreign Certificateholders

     Subject to the discussion of backup withholding below, payments of principal and interest (including any OID) on the equipment notes to, or on behalf of, any beneficial owner of a certificate that is not a U.S. person will not be subject to U.S. federal withholding tax provided that:

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     Any capital gain realized upon the sale, exchange, retirement or other disposition of a certificate or upon receipt of premium paid on an equipment note by a non-U.S. certificateholder will not be subject to U.S. federal income or withholding taxes if (i) such gain is not effectively connected with a U.S. trade or business of the non-U.S. certificateholder and (ii) in the case of an individual, such non-U.S. certificateholder is not present in the United States for 183 days or more in the taxable year of the sale, exchange, retirement or other disposition or receipt.

Backup Withholding

     Payments made on the certificates will not be subject to a backup withholding tax unless, in general, the certificateholder fails to comply with certain reporting procedures or otherwise fails to establish an exemption from such tax under applicable provisions of the Code. Currently, the backup withholding tax rate is 28%.

ERISA CONSIDERATIONS

     Unless otherwise indicated in the applicable prospectus supplement, the certificates may, subject to certain legal restrictions, be purchased and held by an employee benefit plan subject to Title I of the Employee Retirement Income Security Act of 1974, as amended, referred to as “ERISA,” or an individual retirement account or an employee benefit plan subject to section 4975 of the Code. A fiduciary of an employee benefit plan must determine that the purchase and holding of a certificate is consistent with its fiduciary duties under ERISA and does not result in a non-exempt prohibited transaction as defined in section 406 of ERISA or section 4975 of the Code. Employee benefit plans which are governmental plans, as defined in section 3(32) of ERISA, and certain church plans, as defined in section 3(33) of ERISA, are not subject to Title I of ERISA or section 4975 of the Code. The certificates may, subject to certain legal restrictions, be purchased and held by such plans.

PLAN OF DISTRIBUTION

     Certificates may be sold to one or more underwriters for public offering and resale by them. Certificates may also be sold to investors or other persons directly or through one or more dealers or agents. Any underwriter, dealer or agent involved in the offer and sale of the certificates will be named in an applicable prospectus supplement.

     The certificates may be sold:

     Dealer trading may take place in certain of the certificates, including certificates not listed on any securities exchange. We do not intend to apply for listing of the certificates on a national securities exchange. From time to time, we also may authorize underwriters acting as our agents to

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offer and sell the certificates upon the terms and conditions as will be set forth in any prospectus supplement.

     In connection with the sale of certificates, underwriters may be deemed to have received compensation from us in the form of underwriting discounts or commissions and may also receive commissions from purchasers of certificates for whom they may act as agent. Underwriters may sell certificates to or through dealers, and those dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or commissions, which may be changed from time to time, from the purchasers for whom they may act as agent.

     If a dealer is used directly by us in the sale of certificates in respect of which this prospectus is delivered, we will sell the certificates to the dealer, as principal. The dealer may then resell the certificates to the public at varying prices to be determined by the dealer at the time of resale. The dealer will be named in, and the terms of the sale, will be set forth in the applicable prospectus supplement.

     Certificates may be offered and sold through agents designated by us from time to time. The agent involved in the offer or sale of the certificates will be named in, and any commissions payable by us to the agent will be set forth in, the applicable prospectus supplement. Unless otherwise indicated in the applicable prospectus supplement, the agent will be acting on a best efforts basis for the period of its appointment.

     We may solicit directly offers to purchase certificates, and certificates may be sold directly to institutional investors or others who may be deemed to be underwriters within the meaning of the Securities Act with respect to any resale. The terms of these sales will be described in the applicable prospectus supplement. Except as set forth in the applicable prospectus supplement, no director, officer or employee of ours will solicit or receive a commission in connection with direct sales by us of the certificates, although those persons may respond to inquiries by potential purchasers and perform ministerial and clerical work in connection with our direct sales.

     Any underwriting compensation that we pay to underwriters, dealers or agents in connection with the offering of certificates, and any discounts, concessions or commissions allowed by underwriters to participating dealers, will be set forth in an applicable prospectus supplement.

     Underwriters, dealers and agents participating in the distribution of the certificates may be deemed to be underwriters, and any discounts and commissions received by them and any profit realized by them on resale of the certificates may be deemed to be underwriting discounts and commissions under the Securities Act. Underwriters, dealers and agents may be entitled under agreements with us to indemnification against and contribution toward certain civil liabilities, including liabilities under the Securities Act, and to reimbursement by us for certain expenses.

     Underwriters, dealers and agents may engage in transactions with, or perform services for, us and our subsidiaries in the ordinary course of business.

     If so indicated in an applicable prospectus supplement and subject to existing market conditions, we will authorize dealers acting as our agents to solicit offers by certain institutions to purchase certificates from us at the public offering price set forth in the applicable prospectus

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supplement pursuant to delayed delivery contracts. These contracts will provide for payment and delivery on the date or dates stated in the applicable prospectus supplement. Each contract will be for an amount not less than, and the aggregate principal amount of certificates sold pursuant to these contracts will not be less nor more than, the respective amounts stated in the applicable prospectus supplement. Institutions with whom these contracts, when authorized, may be made include commercial and savings banks, insurance companies, pension funds, investment companies, educational and charitable institutions and other institutions, but will in all cases be subject to our approval. These contracts will not be subject to any conditions, except for the condition that the purchase by an institution of the certificates not be prohibited at the time of delivery under the laws of any jurisdiction in the United States to which the institution is subject. A commission set forth in the applicable prospectus supplement will be granted to underwriters and agents soliciting purchases of certificates pursuant to contracts accepted by us. Agents and underwriters will have no responsibility in respect of the delivery or performance of these contracts.

     If an underwriter or underwriters is used in the sale of any certificates, the applicable prospectus supplement will state the intention, if any, of the underwriters at the date of the prospectus supplement to make a market in the certificates. We cannot assure you that there will be a market for the certificates.

     The place and time of delivery for the certificates in respect of which this prospectus is delivered will be set forth in the applicable prospectus supplement.

VALIDITY OF THE CERTIFICATES

     Unless otherwise indicated in the applicable prospectus supplement, the validity of the offered Certificates will be passed upon for us by Deborah Ackerman, Vice President — General Counsel. Ms. Ackerman will rely on the opinion of counsel for Wilmington Trust Company as to certain matters relating to the authorization, execution and delivery of the Certificates by and the valid binding effect on the Trustee.

EXPERTS

     The consolidated financial statements of Southwest Airlines Co. included in Southwest Airlines Co.’s Annual Report (Form 10-K) for the year ended December 31, 2004, and Southwest Airlines Co.’s assessment of the effectiveness of internal control over financial reporting as of December 31, 2004 included therein, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in its reports thereon, included therein, and incorporated herein by reference. Such financial statements and management’s assessment have been incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

     We file annual, quarterly and special reports, proxy statements and other information with the Securities and Exchange Commission. You may read and copy any documents we file at the SEC’s public reference room 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the public reference room. Our SEC filings are also

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available to the public on the SEC’s web site at http://www.sec.gov and through the New York Stock Exchange, 20 Broad Street, New York, New York 10005, on which our common stock is listed.

     The SEC allows us to “incorporate by reference” the information we file with them, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus, and later information that we file with the SEC will automatically update and supersede this information as well as the information included in this prospectus. We incorporate by reference the documents listed below and any future filings made with the SEC under Sections 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934 (excluding any information furnished pursuant to Item 2.02 or 7.01 on any current Report on Form 8-K) until we sell all the Certificates.

     Any party to whom this prospectus is delivered, including a holder in street name, may request a copy of these filings (other than any exhibits unless specifically incorporated by reference into this prospectus), at no cost, by writing or telephoning us at the following address:

Southwest Airlines Co.
Investor Relations
P.O. Box 36611, HDQ-6FC
2702 Love Field Drive
Dallas, Texas 75235
(214) 792-4000

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PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution.

     All amounts above are estimated except for the registration fee.

Item 15. Indemnification of Directors and Officers.

     Article VIII, Section 1 of Southwest’s Bylaws provides as follows:

          “Right to Indemnification: Subject to the limitations and conditions as provided in this Article VIII, each person, who was or is made a party to, or is threatened to be made a party to, any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative, arbitrative or investigative (hereinafter called a “proceeding”), or any appeal in such a proceeding or any inquiry or investigation that could lead to such a proceeding, by reason of the fact that he (or a person of whom he is the legal representative) is or was a director or officer of the corporation (or while a director or officer of the corporation is or was serving at the request of the corporation as a director, officer, partner, venturer, proprietor, trustee, employee, agent, or similar functionary of another foreign or domestic corporation, partnership, joint venture, proprietorship, trust, employee benefit plan, or other enterprise) shall be indemnified by the corporation to the fullest extent permitted by the Texas Business Corporation Act, as the same exists or may hereafter be amended (but, in the case of any such amendment, only to the extent that such amendment permits the corporation to provide broader indemnification rights than said law permitted the corporation to provide prior to such amendment) against judgments, penalties (including excise and similar taxes and punitive damages), fines, settlements and reasonable expenses (including, without limitation, court costs and attorneys’ fees) actually incurred by such person in connection with such proceeding, appeal, inquiry or investigation, and indemnification under this Article VIII shall continue as to a person who has ceased to serve in the capacity which initially entitled such person to indemnity hereunder; provided, however, that in no case shall the corporation indemnify any such person (or the legal representative of any such person) otherwise than for his reasonable expenses, in respect of any proceeding (i) in which such person shall have been finally adjudged by a court of competent jurisdiction (after exhaustion of all appeals therefrom) to be liable on the basis that personal benefit was improperly received by him, whether or not the benefit resulted from an action taken in such person’s official capacity, or (ii) in which such person shall have been found

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liable to the corporation; and provided, further, that the corporation shall not indemnify any such person for his reasonable expenses actually incurred in connection with any proceeding in which he shall have been found liable for willful or intentional misconduct in the performance of his duty to the corporation. The rights granted pursuant to this Article VIII shall be deemed contract rights, and no amendment, modification or repeal of this Article VIII shall have the effect of limiting or denying any such rights with respect to actions taken or proceedings arising prior to any such amendment, modification or repeal. It is expressly acknowledged that the indemnification provided in this Article VIII could involve indemnification for negligence or under theories of strict liability.”

     Article Ten of Southwest’s Articles of Incorporation provides that a director of the corporation shall not be liable to the corporation or its shareholders for monetary damages for an act or omission in the director’s capacity as a director, subject to certain limitations.

     Article 2.02-1B. of the Texas Business Corporation Act provides that, subject to certain limitations, “a corporation may indemnify a person who was, is, or is threatened to be made a named defendant or respondent in a proceeding because the person is or was a director only if it is determined in accordance with Section F of this article that the person: (1) conducted himself in good faith; (2) reasonably believed: (a) in the case of conduct in his official capacity as a director of the corporation, that his conduct was in the corporation’s best interests; and (b) in all other cases, that his conduct was at least not opposed to the corporation’s best interests; and (3) in the case of any criminal proceeding, had no reasonable cause to believe his conduct was unlawful.”

     Southwest also maintains directors’ and officers’ liability insurance.

     The forms of Underwriting Agreement to be filed as Exhibits 1.1 and 1.2 to this Registration Statement provide for indemnification of directors and officers of Southwest against certain liabilities.

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Item 17. Undertakings.

A. The undersigned registrant hereby undertakes:

     (1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

          (i) to include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

          (ii) to reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement; Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 462(b) if, in the aggregate, the changes in volume and price represent no more than 20 percent

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change in the maximum aggregate offering price set forth in the “ Calculation of Registration Fee” table in the effective Registration Statement; and

          (iii) to include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that paragraphs (A)(1)(i) and (A)(1)(ii) do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in periodic reports filed with or furnished to the Commission by the registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement.

     (2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

     (3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

B. The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant’s annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to section 15(d) of the Exchange Act) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

C. Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

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POWER OF ATTORNEY

     Each person whose signature appears below authorizes Gary C. Kelly, Laura Wright, Tammy Romo and Deborah Ackerman, or any of them, to execute in the name of each such person who is then an officer or director of Southwest Airlines Co. (the “Company”) and to file a Registration Statement on Form S-3 relating to debt securities and pass through certificates, and any amendments thereto (and any additional Registration Statement related thereto permitted by Rule 462(b) promulgated under the Securities Act of 1933 (and all further amendments including post-effective amendments thereto)) in each case necessary or advisable to enable the Company to comply with the Securities Act of 1933, as amended, and any rules, regulations and requirements of the Securities and Exchange Commission, in respect thereof, in connection with the registration of the securities which are the subject of such Registration Statements, which amendments may make such changes in such Registration Statements as such attorney may deem appropriate.

SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Registration Statement to be signed on its behalf by the undersigned thereunto duly authorized in the City of Dallas, State of Texas on July 19, 2005.

     Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities indicated on July 19, 2005.

i

ii

INDEX TO EXHIBITS

iii