Chicago-based United was expecting 16 MAX aircraft this year, but deliveries have been frozen since mid-March when regulators worldwide grounded the jet after two deadly crashes in Indonesia and Ethiopia.

"None of Boeing's customers know right now exactly when they're going to get their scheduled MAX deliveries. But one could assume that we won't fully catch up next year," Laderman said.

United has scheduled flights without MAX till Nov. 3 and executives said they do not expect the aircraft, which still needs regulatory approval for new software and pilot training, to fly anytime before.

(Reporting by Sanjana Shivdas in Bengaluru and Tracy Rucinski in Nerja, Spain; Editing by Shinjini Ganguli)

Stocks treated in this article : Boeing Company (The), United Continental Holdings Inc