Supplemental Agreement No. 37 to Purchase Agreement No. 1977 between The Boeing Company and American Airlines, Inc. for Boeing 737-800 Aircraft

Exhibit 10.4

Supplemental Agreement No. 37

to

Purchase Agreement No. 1977

between

The Boeing Company

and

American Airlines, Inc.

Relating to Boeing Model 737-800 Aircraft

THIS SUPPLEMENTAL AGREEMENT, entered into as of April 25, 2014, (Supplemental Agreement Number 37) by and between THE BOEING COMPANY, a Delaware corporation with offices in Seattle, Washington, (Boeing) and AMERICAN AIRLINES, INC., a Delaware corporation with offices in Fort Worth, Texas, together with its successors and permitted assigns (Customer);

WHEREAS, Boeing and Customer entered into Purchase Agreement No. 1977 dated October 31, 1997, relating to Boeing Model 737-823 aircraft, as amended and supplemented (the “Purchase Agreement”) and capitalized terms used herein without definitions shall have the meanings specified therefore in such Purchase Agreement;

WHEREAS, Boeing and Customer desire to revise the delivery of the 737-823 aircraft delivering in [*CTR] 2015 to [*CTR] 2015 agreeing to [*CTR] to [*CTR] 2015 and to [*CTR] to the existing [*CTR] 2015 [*CTR].

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

1. Table of Contents:

The “Table of Contents” to the Purchase Agreement is deleted in its entirety and a revised “Table of Contents,” attached hereto and identified with an “SA-37” legend is substituted in lieu thereof to reflect the changes made by this SA-37.

SPH ###-###-####-6

BOEING PROPRIETARY

[*CTR]=[CONFIDENTIAL PORTION OMITTED AND FILED SEPARATELY WITH THE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]

2. Revision of Table 1F:

Table 1F entitled “Aircraft Delivery, Description, Price and Advance Payments – Purchased Aircraft” is deleted in its entirety and a revised Table 1F to revise the [*CTR] 2014 delivery to [*CTR] 2015, attached hereto and identified with an “SA-37” legend is substituted in lieu thereof to reflect the changes made by this SA-37.

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

BOEING PROPRIETARY

[*CTR]=[CONFIDENTIAL PORTION OMITTED AND FILED SEPARATELY WITH THE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]

TABLE OF CONTENTS

[*CTR]=[CONFIDENTIAL PORTION OMITTED AND FILED SEPARATELY WITH THE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]

TABLE OF CONTENTS, continued

[*CTR]=[CONFIDENTIAL PORTION OMITTED AND FILED SEPARATELY WITH THE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]

TABLE OF CONTENTS, continued

[*CTR]=[CONFIDENTIAL PORTION OMITTED AND FILED SEPARATELY WITH THE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]

Table 1F To Purchase Agreement No. 1977

737-800 Aircraft Delivery, Description, Price and Advance Payments Purchased Aircraft

[*CTR]=[CONFIDENTIAL PORTION OMITTED AND FILED SEPARATELY WITH THE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]

Table 1F To Purchase Agreement No. 1977

737-800 Aircraft Delivery, Description, Price and Advance Payments Purchased Aircraft

[*CTR]=[CONFIDENTIAL PORTION OMITTED AND FILED SEPARATELY WITH THE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]

Table 1F To Purchase Agreement No. 1977

737-800 Aircraft Delivery, Description, Price and Advance Payments Purchased Aircraft

[*CTR]=[CONFIDENTIAL PORTION OMITTED AND FILED SEPARATELY WITH THE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]

Table 1F To Purchase Agreement No. 1977

737-800 Aircraft Delivery, Description, Price and Advance Payments Purchased Aircraft

[*CTR]=[CONFIDENTIAL PORTION OMITTED AND FILED SEPARATELY WITH THE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]

Table 1F To Purchase Agreement No. 1977

737-800 Aircraft Delivery, Description, Price and Advance Payments Purchased Aircraft

[*CTR]=[CONFIDENTIAL PORTION OMITTED AND FILED SEPARATELY WITH THE COMMISSION PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT]