Exhibit 10.29

LETTER AGREEMENT NO. 2

As of March 5, 2010

United Air Lines, Inc.

77 West Wacker Drive

Chicago, Illinois 60601

Re: PREDELIVERY PAYMENTS

Dear Ladies and Gentlemen,

United Air Lines, Inc. (the “Buyer”), and AIRBUS S.A.S. (the “Seller”), have entered into an Airbus A350-900XWB Purchase Agreement dated as of even date herewith (the “Agreement”), which covers, among other things, the sale by the Seller and the purchase by the Buyer of certain Aircraft, under the terms and conditions set forth in said Agreement. The Buyer and the Seller have agreed to set forth in this Letter Agreement No. 2 (the “Letter Agreement”) certain additional terms and conditions regarding the sale of the Aircraft. Capitalized terms used herein and not otherwise defined in this Letter Agreement will have the meanings assigned thereto in the Agreement. The terms “herein,” “hereof” and “hereunder” and words of similar import refer to this Letter Agreement.

Both parties agree that this Letter Agreement will constitute an integral, nonseverable part of said Agreement, that the provisions of said Agreement are hereby incorporated herein by reference, and that this Letter Agreement will be governed by the provisions of said Agreement, except that if the Agreement and this Letter Agreement have specific provisions which are inconsistent, the specific provisions contained in this Letter Agreement will govern.

AIRBUS S.A.S. & UNITED AIR LINES, INC. – PROPRIETARY AND CONFIDENTIAL

[CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT].

[CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT].

[CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT].

[CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT].

“Taxes” means any present or future tax, stamp or other taxes, levies, imposts, duties, charges, fees, deductions or withholdings, now or hereafter imposed, levied, collected, withheld or assessed by any governmental authority or any political subdivision or taxing authority thereof or therein.

AIRBUS S.A.S. & UNITED AIR LINES, INC. – PROPRIETARY AND CONFIDENTIAL

Notwithstanding any other rights the Seller may have at contract or at law, the Buyer and the Seller hereby agree that should any amount (whether under this Agreement or under any other agreement between the Buyer or a direct or indirect subsidiary of the Buyer on the one hand and the Seller and the Seller Affiliates on the other hand) become due and payable by the Buyer or the Buyer Affiliates, [CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]

If any Predelivery Payment due the Seller is not received by the Seller on the date or dates agreed upon between the Buyer and the Seller, the Seller will have the right to claim from the Buyer and the Buyer will promptly pay to the Seller upon receipt of such claim, interest at the rate of [CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]. The Seller’s right to receive such interest will be in addition to any other rights of the Seller hereunder or at law. [CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT].

Notwithstanding any provision of law to the contrary, the Buyer will not, by virtue of anything contained in this Agreement (including, without limitation, [CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] or Predelivery Payments hereunder, or any designation or identification by the Seller of a particular aircraft as an Aircraft to which any of the provisions of this Agreement refers) acquire any proprietary, insurable or other interest whatsoever in any Aircraft before Delivery of and payment for such Aircraft, as provided in this Agreement.

[CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT].

[CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT].

AIRBUS S.A.S. & UNITED AIR LINES, INC. – PROPRIETARY AND CONFIDENTIAL

This Letter Agreement and the rights and obligations of the parties will be subject to the provisions of Clause 21 of the Agreement.

This Letter Agreement is subject to the terms and conditions of Clause 22.10 of the Agreement.

This Letter Agreement may be executed by the parties hereto in separate counterparts, each of which when so executed and delivered shall be an original, but all such counterparts shall together constitute one and the same instrument.

AIRBUS S.A.S. & UNITED AIR LINES, INC. – PROPRIETARY AND CONFIDENTIAL

If the foregoing correctly sets forth our understanding, please execute the original and one (1) copy hereof in the space provided below and return a copy to the Seller.

AIRBUS S.A.S. & UNITED AIR LINES, INC. – PROPRIETARY AND CONFIDENTIAL