Supplemental Agreement No. 5 to Purchase AgreementNo. 3860 between TheBoeing Company and UnitedAirlines, Inc. Relating to Boeing Model 787 Aircraft

Exhibit 10.8

CONFIDENTIAL MATERIAL APPEARING IN THIS DOCUMENT HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION IN ACCORDANCE WITH THE SECURITIES ACT OF 1933, AS AMENDED, AND RULE 24B-2 PROMULGATED THEREUNDER. OMITTED INFORMATION HAS BEEN REPLACED WITH ASTERISKS.

Supplemental Agreement No. 5

to

Purchase Agreement No. 3860

between

The Boeing Company

and

United Airlines, Inc.

Relating to Boeing Model 787 Aircraft

THIS SUPPLEMENTAL AGREEMENT, entered into as of April 30, 2015, by and between THE BOEING COMPANY (Boeing) and UNITED AIRLINES, INC. (a Delaware corporation formerly known as Continental Airlines, Inc. and successor by merger to United Air Lines, Inc.) (Customer);

WHEREAS, the parties hereto entered into Purchase Agreement No. 3860 dated September 27, 2012, as amended and supplemented (Purchase Agreement), relating to the purchase and sale of Boeing model 787 aircraft (Aircraft). This Supplemental Agreement is an amendment to the Purchase Agreement;

WHEREAS, Boeing and Customer wish to *** the following firm 787-9 Aircraft *** this Purchase Agreement:

WHEREAS, Boeing and Customer agree to *** the following *** firm 787-*** Aircraft and *** them with *** 787-*** Aircraft in the same delivery months:

WHEREAS, Boeing and Customer agree to apply *** firm Aircraft *** under this Supplemental Agreement No. 05 *** for the *** new model 787-*** Aircraft added under this Supplemental Agreement No. 05 and *** Customer’s *** for 787 aircraft.

NOW THEREFORE, in consideration of the mutual covenants herein contained, the parties agree to amend the Purchase Agreement as follows:

1. Table of Contents and Articles.

The “Table of Contents” is deleted in its entirety and replaced with the attached “Table of Contents” (identified by “SA-5”).

2. Tables.

3. Letter Agreements.

The Purchase Agreement will be deemed to be supplemented to the extent herein provided as of the date hereof and as so supplemented will continue in full force and effect.

EXECUTED IN DUPLICATE as of the day and year first written above.

TABLE OF CONTENTS

TABLE OF CONTENTS, CONTINUED

Table 1 to Purchase Agreement No. 3860

787-10 Aircraft with GENX-1B*** Engines Delivery, Description, Price and Advance Payments

(787-10/GE/***)

Table 1 to Purchase Agreement No. 3860

787-10 Aircraft with GENX-1B*** Engines Delivery, Description, Price and Advance Payments

(787-10/GE/***)

Attachment B-1 to Letter Agreement UAL-PA-03860-LA-120965R1

787-10 Option Aircraft with GENX-1B***

Engines Delivery, Description, Price and Advance Payments

(787-10/GE/***)

Attachment B-1 to Letter Agreement UAL-PA-03860-LA-120965R1

787-10 Option Aircraft with GENX-1B***

Engines Delivery, Description, Price and Advance Payments

(787-10/GE/***)

UAL-PA-03860-LA-1209413A1R1

United Airlines, Inc.

233 South Wacker Drive

Chicago, Illinois 60606

This letter agreement UAL-PA-03860-LA-1209413A1R1 (Amending Letter Agreement) amends and supplements the Purchase Agreement, amends certain terms in Letter Agreement UAL-PA-03860-LA-1209413 (the Letter Agreement), and supersedes and replaces in its entirety letter agreement UAL-PA-03860-LA-1209413A1. All terms used and not defined in this Letter Agreement have the same meaning as in the Purchase Agreement.

Article 4.4 of the Letter Agreement is hereby deleted and replaced with the following:

Boeing and Customer understand that certain information contained in this Letter Agreement, including any attachments hereto, is considered by both parties to be confidential. Boeing and Customer agree that each party will treat this Letter Agreement and the information contained herein as confidential and will not, without the other party’s prior written consent, disclose this Letter Agreement or any information contained herein to any other person or entity except as may be required by applicable law or governmental regulations.

Very truly yours,

BOEING / UNITED AIRLINES, INC. PROPRIETARY