Exhibit 10.17 6-1162-MDH-150 July 12, 1996 United Air Lines, Inc. P.O. Box 66100 Chicago, Illinois 60666 Subject: Letter Agreement No. 6-1162-MDH-150 to Purchase Agreement No. 1485, 1595, 1602, 1663 and 1670 - [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] Gentlemen: Reference is made to Purchase Agreement Nos. 1485, 1595, 1602, 1663 and 1670 (each individually a "Purchase Agreement", and collectively the "Purchase Agreements") between The Boeing Company ("Boeing") and United Air Lines, Inc. ("Buyer") relating to the sale by Boeing and the purchase by Buyer of 737, 747, 757, 767 and 777 aircraft (hereinafter referred to as the Aircraft). This letter agreement ("Letter Agreement"), when accepted by Buyer, will become part of each Purchase Agreement and will evidence our further agreement with respect to the matters set forth below. All terms used herein and in the Purchase Agreements, not defined herein, shall have the same meaning as in such Purchase Agreements. If there is any inconsistency between the terms of this Letter Agreement and any such Purchase Agreement or any Purchase Agreement Amendment thereto the terms of this Letter Agreement will govern. United Air Lines, Inc. 6-1162-MDH-150 Page 2 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] Supplemental Agreement No. 6 dated May 30, 1996 to Purchase Agreement No. 1485 Supplemental Agreement No. 7 dated July 11, 1996 to Purchase Agreement No. 1485 Supplemental Agreement No. 4 dated May 30, 1996 to Purchase Agreement No. 1663 Supplemental Agreement No. 5 dated July 11, 1996 to Purchase Agreement No. 1663 Supplemental Agreement No. 8 dated May 30, 1996 to Purchase Agreement No. 1670 Supplemental Agreement No. 9 dated July 11, 1996 to Purchase Agreement No. 1670 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] United Air Lines, Inc. 6-1162-MDH-150 Page 3 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] United Air Lines, Inc. 6-1162-MDH-150 Page 4 A = B x C/(D-E) where A = [*CONFIDENTIAL MATERIAL OMITTED B = AND FILED SEPARATELY WITH c = THE SECURITIES AND EXCHANGE D = COMMISSION PURSUANT TO A REQUEST E = FOR CONFIDENTIAL TREATMENT] [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] 1.2.1 Letter Agreement No. 1670-5R dated as of December 18, 1990, accepted and agreed to by Buyer on August 2, 1991 is amended to delete the Model 747-422 Option Aircraft listed in Attachment No. 2 hereto, and as so amended such Letter Agreement No. 1670-5R shall remain in full force and effect, and 1.2.2 the following letter agreements shall be deemed canceled and of no further force and effect: Letter Agreement No. Purchase Agreement Title No. - -------------------- ----- ------------------ 1485-8* Option Aircraft (Block E) 1485 1663-5 Option Aircraft 1663 1595-4 Option Aircraft 1595 United Air Lines, Inc. 6-1162-MDH-150 Page 5 Notwithstanding the cancellation of Letter Agreement No. 1485-8, Boeing and Buyer agree the provisions of paragraph 11. [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] of Letter Agreement No. 6-1162-TML-388 shall be applicable to the [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] United Air Lines, Inc. 6-1162-MDH-150 Page 6 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] United Air Lines, Inc. 6-1162-MDH-150 Page 7 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] United Air Lines, Inc. 6-1162-MDH-150 Page 8 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] United Air Lines, Inc. 6-1162-MDH-150 Page 9 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] United Air Lines, Inc. 6-1162-MDH-150 Page 10 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] United Air Lines, Inc. 6-1162-MDH-150 Page 11 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] United Air Lines, Inc. 6-1162-MDH-150 Page 12 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] United Air Lines, Inc. 6-1162-MDH-150 Page 13 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] United Air Lines, Inc. 6-1162-MDH-150 Page 14 4. Confidentiality. --------------- This Letter Agreement is subject to the confidentiality provisions of the following Letter Agreements. Letter Agreement No. Purchase Agreement No. - -------------------- ---------------------- 6-1162-GKW-132 1485 6-1162-DLJ-886 1670 6-1162-DLJ-832 1663 6-1162-GKW-653 1595 If the foregoing correctly sets forth your understanding of our agreement with respect to the matters treated above. please indicate your acceptance and approval below. Very truly yours, THE BOEING COMPANY By /s/ M. O. Hunt -------------- Its Attorney in Fact ---------------- ACCEPTED AND AGREED TO this Date: July 12, 1996 UNITED AIR LINES, INC. By Douglas A. Hacker ----------------- Its Senior Vice President and ------------------------- Chief Financial Officer ----------------------- Attachment No. 1 to 6-1162-MDH-150 Page 1 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] Attachment No. 1 to 6-1162-MDH-150 Page 1 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] Attachment No. 1 to 6-1162-MDH-150 Page 1 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] Attachment No. 1 to 6-1162-MDH-150 Page 1 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] Attachment No. 4 to 6-1162-MDH-150 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] Attachment No. 5 to 6-1162-MDH-150 Page 1 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] Attachment No. 6 to 6-1162-MDh-150 Page 1 [*CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]