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Delta has cancelled an order for 20 used Embraer E190 and 40 new Boeing 737-900ER aircraft after pilots rejected a tentative contract proposal.

“Those orders will be cancelled,” CEO Richard Anderson said during the airline’s quarterly earnings call on Wednesday. The order required the ratification of the contract to proceed.

The E190 aircraft were planned to enter the mainline fleet in the fourth quarter of 2016. The 737-900ERs, which were in addition to an existing order, were to be deployed as replacements for other narrowbody aircraft scheduled to retire through 2019.