Supplemental Agreement No. 07 to Purchase Agreement NumberPA-03784 Between The BoeingCompany and UnitedAirlines, Inc. Relating to Boeing Model 737 Aircraft

Exhibit 10.6

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. 07

to

Purchase Agreement Number PA-03784

Between

The Boeing Company

and

United Airlines, Inc.

Relating to Boeing Model 737 Aircraft

THIS SUPPLEMENTAL AGREEMENT is entered into as of May 26, 2015 by and between THE BOEING COMPANY (Boeing) and UNITED AIRLINES, INC. (formerly known as Continental Airlines, Inc. and successor by merger to United Air Lines, Inc.) (Customer);

WHEREAS, the parties hereto entered into Purchase Agreement Number PA-03784 dated July 12, 2012 (Purchase Agreement), as amended and supplemented, relating to the purchase and sale of Boeing Model 737 aircraft (Aircraft). This Supplemental Agreement is an amendment to the Purchase Agreement;

WHEREAS, Boeing and Customer agree to ***:

WHEREAS, Boeing and Customer agree to reschedule the delivery of *** Option Aircraft from *** to ***; and

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

1.1 The “Table of Contents” is deleted in its entirety and replaced with the attached “Table of Contents” (identified by “SA-7”).

1.2 “Attachment A to Letter Agreement UAL-PA-03784-LA-1207879” is deleted in its entirety and replaced with the attached “Attachment A to Letter Agreement UAL-PA-03784-LA-1207879” (identified by “SA-7”).

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.

Supplemental Agreement No. 07 to

Purchase Agreement PA-03784

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

TABLE OF CONTENTS

BOEING / UNITED AIRLINES, INC. PROPRIETARY

Attachment A to

Letter Agreement UAL-PA-03784-LA-1207879

737-900ER Option Aircraft Delivery, Description, Price and Advance Payments

Attachment A to

Letter Agreement UAL-PA-03784-LA-1207879

737-900ER Option Aircraft Delivery, Description, Price and Advance Payments