Delta Air Lines (DAL) 10-Q 2017 Q3 Quarterly report

Exhibit 15

October 11, 2017

The Board of Directors and Stockholders of

Delta Air Lines, Inc.

We are aware of the incorporation by reference in the Registration Statements (Form S-3 No.’s 333-206258, 333-209571, and 333-216463, and Form S-8 No.’s 333-142424, 333-149308, 333-154818, 333-151060, and 333-212525) of Delta Air Lines, Inc. for the registration of its securities of our report dated October 11, 2017 relating to the unaudited condensed consolidated interim financial statements of Delta Air Lines, Inc. that are included in its Form 10-Q for the quarter ended September 30, 2017.

/s/ Ernst & Young LLP