American Airlines will now mandate vaccinations for all workers.
It will apply to all US employees and some based overseas.
The airline says stricter government requirements apply as the Biden Administration considers it a government contractor.
It will impact about 100,000 employees.
JetBlue and Alaska Airlines will also mandate vaccinations for all workers.
The White House has been putting pressure on airlines to get workers vaccinated by early December.
Due to its air transport agreements with the government, it is regarded as a federal contractor, American says.
AA says regular testing won’t be offered an as alternative to getting vaccinated but medical or religious exemptions will be considered.
"It is clear that team members who choose to remain unvaccinated will not be able to work at American Airlines," AA CEO Doug Parker and President Robert Isom said in an employee memo.
The Allied Pilots Association union says about 70% of the 14,000 American Airlines pilots it represents are vaccinated.
"APA is neither anti-vaccine, nor anti-mandate, but we insist on a path forward that takes into consideration our pilots’ needs and concerns while promoting a safe and healthy workplace," the union said.
JetBlue and Alaska Airlines informed workers the vaccine mandate would be implemented on December 8, the day the White House requires all federal contractors to be vaccinated.
