CHICAGO (Reuters) – United Airlines (UAL.O) is preparing for the biggest pilot furloughs of its history after announcing on Thursday the need to cut 2,850 pilot jobs this year, or about 21% of the total, without further U.S. government aid.

Airlines, reeling from the devastating impact of the novel coronavirus pandemic on air travel, have asked the U.S. government for another $25 billion to cover employee payroll through March.

The first tranche, which banned any job cuts until Oct. 1, expires at the end of September, but talks in Washington have stalled as Congress has struggled to reach agreement on a broader coronavirus assistance package.

United’s planned cuts, released in a memo to employees and shared with the media, would run between Oct. 1 and Nov. 30. They are significantly higher than the 1,900 announced earlier this week by Delta Air Lines (DAL.N) and 1,600 by American Airlines (AAL.O).

Facing a shrinking industry in the years ahead, airlines have generally tried to mitigate the number of forced job cuts by offering early retirement or voluntary departure deals, but some carriers’ packages have been more attractive than others.

“While other airlines have chosen to reduce manpower through voluntary means, it is tragic that United has limited those options for our pilots and instead has chosen to furlough more pilots than ever before in our history,” the union representing United’s 13,000 pilots said in a statement.

United said the numbers were based on current travel demand for the remainder of the year and its anticipated flying schedule, which it said “continues to be fluid with the resurgence of COVID-19 in regions across the U.S.”

Chicago-based United is more exposed than its peers to international travel, which is expected to take longer to rebound from the pandemic.

United, which has warned that 36,000 jobs are on the line across the company, has not yet provided final furlough numbers for other work groups.

American said on Tuesday it was cutting 19,000 jobs in addition to voluntary reductions that will see the company’s workforce shrink by about 30%.

United’s announcement comes on the final day of the Republican National Convention, where President Donald Trump will try to regain momentum against the backdrop of a pandemic that has killed over 180,000 Americans and produced a recession that has resulted in the loss of millions of jobs.