Table of Contents Filed pursuant to Rule 424(b)(5) Registration No. 333-143865 The information in this preliminary prospectus supplement is not complete and may be changed. We may not deliver these securities until a prospectus supplement is delivered in final form. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities and we are not soliciting offers to buy these securities in any jurisdiction where the offer or sale is not permitted. PROSPECTUS SUPPLEMENT (Subject to Completion, dated October 5, 2009) (To Prospectus dated June 19, 2007) $659,107,000 United Air Lines, Inc. 2009-1 Pass Through Trust PASS THROUGH CERTIFICATES, SERIES 2009-1 This prospectus supplement relates to new pass through certificates to be issued by a pass through trust to be formed by United. Each certificate will represent an interest in the pass through trust. The certificates do not represent interests in or obligations of United or any of its affiliates. The proceeds from the sale of the certificates will initially be held in escrow. The pass through trust will use the escrowed funds to acquire equipment notes. The equipment notes will be issued by United to finance sixteen (16) Airbus aircraft and fifteen (15) Boeing aircraft owned by United. Payments on the equipment notes held in the pass through trust will be passed through to the certificateholders. Interest on the equipment notes held in the pass through trust will be payable on May 1 and November 1 of each year, beginning on May 1, 2010. Principal paid on the equipment notes will be payable on May 1 and November 1 in scheduled years, beginning on May 1, 2010. Distributions on the certificates will be subject to certain subordination provisions as described herein. Morgan Stanley Bank, N.A. will provide a liquidity facility for the certificates. The liquidity facility is expected to provide an amount sufficient to pay up to three semiannual interest payments on the certificates. The payment obligations of United under the equipment notes will be fully and unconditionally guaranteed by UAL. Investing in the pass through certificates involves risks. See “RISK FACTORS” beginning on page S-13. Face Stated Final Expected Amount Interest Rate Distribution Date Price to Public(1) $659,107,000 % November 1, 2016 100% (1) Plus accrued interest, if any, from the date of issuance. The underwriters will purchase all of the certificates if any are purchased. The aggregate proceeds from the sale of the certificates will be $659,107,000. United will pay the underwriters a commission of $ . The underwriters expect to deliver the certificates to purchasers on October , 2009. The certificates will not be listed on any national securities exchange. The Securities and Exchange Commission (the “SEC”) and state securities regulators have not approved or disapproved these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense. Joint Bookrunners J.P. MORGAN MORGAN STANLEY Co-Manager Goldman, Sachs & Co. October , 2009 Table of Contents TABLE OF CONTENTS Prospectus Supplement Page Presentation of Information S-iii Summary S-1 Risk Factors S-13 Use of Proceeds S-17 Management’s Discussion and Analysis of Financial Condition and Results of Operations S-18 Business S-73 Description of the Certificates S-85 Description of the Deposit Agreement S-101 Description of the Escrow Agreement S-103 Description of the Liquidity Facility S-104 Description of the Intercreditor Agreement S-110 Description of the Aircraft and the Appraisals S-116 Description of the Equipment Notes S-119 Possible Issuance of Additional Certificates S-128 Certain United States Federal Income Tax Considerations S-129 Certain Delaware Taxes S-134 Certain ERISA Considerations S-135 Underwriting S-137 Notice to Canadian Residents S-139 Legal Matters S-140 Structuring Advisor S-140 Experts S-140 Incorporation of Certain Documents by Reference S-141 Appendix I Glossary I-1 Appendix II Appraisals II-1 Appendix III Loan to Value Ratio Tables III-1 S-i Table of Contents TABLE OF CONTENTS Prospectus About This Prospectus 1 Cautionary Statement Concerning Forward-Looking Statements 1 Where You Can Find More Information 2 Incorporation of Certain Documents By Reference 3 Ratio of Earnings to Fixed Charges 4 Legal Matters 5 Experts 5 You should rely only on the information contained in this prospectus supplement and the accompanying prospectus and the documents incorporated by reference in this prospectus supplement and the accompanying prospectus. We have not authorized anyone to provide you with information that is different. If anyone provides you with different or inconsistent information, you should not rely on it. This document may be used only where it is legal to sell these securities. You should not assume that the information in this prospectus supplement and the accompanying prospectus is accurate as of any date other than the date of this prospectus supplement. Also, you should not assume that there has been no change in the affairs of United or UAL since the date of this prospectus supplement. S-ii Table of Contents PRESENTATION OF INFORMATION These offering materials consist of two documents: (1) this prospectus supplement, which describes the terms of the certificates that we are currently offering and (2) the accompanying prospectus, which provides general information about us and our certificates, some of which may not apply to the certificates that we are currently offering. The information in this prospectus supplement replaces any inconsistent information included in the accompanying prospectus. We have given certain terms specific meanings for purposes of this prospectus supplement. The “Glossary” attached as Appendix I to this prospectus supplement defines each of these terms. At varying places in this prospectus supplement and the accompanying prospectus, we refer you to other sections of the documents for additional information by indicating the caption heading of the other sections. The page on which each principal caption included in this prospectus supplement and the accompanying prospectus can be found is listed in the table of contents on the preceding page. All cross references in this prospectus supplement are to captions contained in this prospectus supplement and not in the accompanying prospectus, unless otherwise stated. Certain statements contained in or incorporated by reference in this prospectus supplement and the accompanying prospectus are forward-looking and thus reflect United Air Lines, Inc.’s and UAL Corporation’s (together with their respective consolidated subsidiaries, “United” and “UAL”, respectively) current expectations and beliefs with respect to certain current and future events and financial performance. Such forward-looking statements are and will be subject to many risks and uncertainties relating to our operations and business environment that may cause actual results to differ materially from any future results expressed or implied in such forward-looking statements. Words such as “expects,” “will,” “plans,” “anticipates,” “indicates,” “believes,” “forecast,” “guidance,” “outlook” and similar expressions are intended to identify forward-looking statements. Additionally, forward-looking statements include statements that do not relate solely to historical facts, such as statements which identify uncertainties or trends, discuss the possible future effects of current known trends or uncertainties, or which indicate that the future effects of known trends or uncertainties cannot be predicted, guaranteed or assured. All forward-looking statements contained in or incorporated by reference in this prospectus supplement and the accompanying prospectus are based upon information available to us on the date such statements are made. We undertake no obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events, changed circumstances or otherwise. UAL’s and United’s actual results could differ materially from these forward-looking statements due to numerous factors including, without limitation, the following: our ability to comply with the terms of our amended credit facility and other financing arrangements; the costs and availability of financing; our ability to maintain adequate liquidity; our ability to execute our operational plans; our ability to control our costs, including realizing benefits from our resource optimization efforts and cost reduction initiatives; our ability to utilize our net operating losses; our ability to attract and retain customers; demand for transportation in the markets in which we operate; an outbreak of a disease that affects travel demand or travel behavior; demand for travel and the impact the economic recession has on customer travel patterns; the increasing reliance on enhanced video-conferencing and other technology as a means of conducting virtual meetings; general economic conditions (including interest rates, foreign currency exchange rates, investment or credit market conditions, crude oil prices, costs of aviation fuel and refining capacity in relevant markets); our ability to cost-effectively hedge against increases in the price of aviation fuel; any potential realized or unrealized gains or losses related to fuel or currency hedging programs; the effects of any hostilities, act of war or terrorist attack; the ability of other air carriers