Delta Air Lines said it will likely furlough nearly 2,000 pilots in October.
It says it hopes to avoid this and is still in talks with the Air Line Pilots Association over cost cutting measures.
Last month it proposed a pay cut of 15% to pilots.
Federal payroll assistance runs out on 30 September when US airlines are able to cut jobs if needed.
There could be tens of thousands across the industry.
"We are six months into this pandemic and only 25% of our revenues have been recovered," John Laughter, Delta’s senior vice president of flight operations wrote in a memo to pilots.
"We are simply overstaffed, and we are faced with an incredibly difficult decision."
The union says it has offered ‘countless voluntary options to management to prevent furloughs from occurring’ and still hopes they can be avoided.
"It’s not too late for management to complete discussions at the bargaining table and help mitigate the need to furlough," said union spokesman Chris Riggins.
Delta said its chief operating officer Gil West will retire at the end of September after more than a decade with the airline.
He has been Delta’s COO since 2014.
Written by Ray Montgomery, US editor
