Supplemental Agreement No. 06 to Purchase Agreement NumberPA-03784 (the Agreement) Between The Boeing Company and United Airlines, Inc. Relating to Boeing Model 737-900ER Aircraft

Exhibit 10.3

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. 06

to

Purchase Agreement Number PA-03784

(the Agreement)

Between

The Boeing Company

and

United Airlines, Inc.

Relating to Boeing Model 737-900ER Aircraft

THIS SUPPLEMENTAL AGREEMENT is entered into as of June 6, 2014 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 revise the delivery month for the following Aircraft:

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

1.1 Remove and replace, in its entirety, the “Table of Contents”, with the “Table of Contents” attached hereto, to reflect the changes made by this Supplemental Agreement No. 06.

1.2 Remove and replace, in its entirety, “Table 1” with the “Table 1” attached hereto to reflect the above revisions.

The 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. 06 to

Purchase Agreement PA-03784

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

TABLE OF CONTENTS

BOEING / UNITED AIR LINES, INC. PROPRIETARY

BOEING / UNITED AIR LINES, INC. PROPRIETARY

BOEING / UNITED AIR LINES, INC. PROPRIETARY

Table 1

Purchase Agreement No. 03784

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