New York, United States | AFP

United Airlines said Wednesday it plans to lay off up to 16,000 workers amid a prolonged industry downturn due to the coronavirus and the continuing stalemate in Washington over further federal support for the industry.

The big US carrier, which had previously said as many as 36,000 workers could be terminated, said early retirement and other programs had lessened the need for even deeper job cuts, but the "devastating" impact of Covid-19 on airline travel still required layoffs.

But even with voluntary programs and other cost-cutting, the savings "have not been enough to avoid involuntary furloughs entirely," the company said.

"Today, each of our operations leaders communicated directly with their teams to share the heart-wrenching news that approximately 16,000 United employees will be notified of an involuntary furlough effective as early as October 1."

The announcement comes on the heels layoff warnings from American Airlines and Delta Air Lines.

Unions representing flight attendants, pilots and other airline workers are holding rallies and engaging in letter-writing campaigns to prod Congress to roll out another round of support that would avert layoffs.

So far, progress on the package has been stymied by partisan gridlock in Washington.

"Flight attendants are resilient in the face of adversity, 1st responders. Pilots spend years training to acquire skills & knowledge to fly the public safety," the Association of Flight Attendants tweeted late Tuesday.

"Inaction by Congress will now send us to the unemployment line."

- Long downturn -

United's cuts affect nearly 7,000 flight attendants and almost 3,000 pilots, among other staff.

"The pandemic has drawn us in deeper and lasted longer than almost any expert predicted, and in an environment where travel demand is so depressed, United cannot continue with staffing levels that significantly exceed the schedule we fly," the company said.

 "Sadly, we don't expect demand to return to anything resembling normal until there is a widely available treatment or vaccine."

Last week, American Airlines said it would furlough around 19,000 staff members if federal funding is not approved. Delta Air Lines has also signaled that 1,900 pilots could be furloughed.

"If we can't and don't get the extension, we'll be forced to go ahead with the furlough," Delta Chief Executive Ed Bastian told CNBC earlier this week.

All the major US carriers qualified for support under a $25 billion federal funding under the $2.2 trillion CARES Act in March, which barred involuntary staff cuts through the end of September.

Another round of federal support for airline workers has garnered some bipartisan support on Capitol Hill. An August 5 letter signed by 16 Republican senators called for a "clean extension of payroll support ... to avoid furloughs and further support those workers." 

Critics question the fairness of supporting the air travel industry over other embattled sectors and say the money discouraged needed restructuring. 

The potential funding has been hung up in a fight between the White House and Democratic leaders over the size of the package and other hot-button issues, such as funding for voting-by-mail during the pandemic and support for state and local governments.

United encouraged staff to keep advocating for the bill.

"Many of you have participated in an effort to write to your representatives and advocate for an extension. If you haven't and you'd still like to lend your voice, click here to take action," United said in the memo that included a link to a form to reach lawmakers.