Exhibit 10.17

6-1162-ELP-0787

United Air Lines, Inc.

P. O. Box 60100

Chicago, IL
60601-0100



|           |  |                                                                                                                                                                       
|---------- |  | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------
|Subject:   |  | [CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT] Guarantee for 787-9                                
|           | 
|Reference: |  | Purchase Agreement No. 3427 (Purchase Agreement) between The Boeing Company (Boeing) and United Air Lines, Inc. (Customer) relating to Model 787-9 aircraft
(Aircraft)

This letter agreement (Letter Agreement) amends and supplements the Purchase Agreement. All terms used but not
defined in this Letter Agreement have the same meaning as in the Purchase Agreement.

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

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

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

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

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

5. Assignment.

The rights and obligations described in this Letter Agreement are provided to Customer in consideration of Customer becoming the operator
of the Aircraft and can only be assigned, in whole or in part, pursuant to Article 9 of the AGTA as amended by Letter Agreement No. 6-1162-IRS-0184.

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

P.A. No. 3427

[CONFIDENTIAL MATERIAL
OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]_Guarantee_787-9

BOEING / UNITED PROPRIETARY



---

United Air Lines, Inc.

6-1162-ELP-0787

Page 2



7. Confidential Treatment.

Customer and Boeing understand that certain commercial and financial information contained in this Letter Agreement are considered by
Boeing and Customer as confidential and are subject to the terms and conditions set forth in Letter Agreement No. 6-1162-IRS-0182.

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/ Nobuko Wiles
|                            | 
|Its                         |  | Attorney-In-Fact
|                           
|ACCEPTED AND AGREED TO this
|                           
|Date: February 19, 2010    
|                           
|UNITED AIR LINES, INC.     

|    |  |                                                     
|--- |  | ----------------------------------------------------
|    | 
|By  |  | /s/ Kathryn A. Mikells                              
|    | 
|Its |  | Executive Vice President and Chief Financial Officer



P.A. No. 3427

[CONFIDENTIAL MATERIAL OMITTED AND FILED SEPARATELY WITH THE SEC PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]_Guarantee_787-9

BOEING / UNITED PROPRIETARY