Nearly 600 United Airlines employees face being fired after failing to comply with the firm's Covid-19 vaccination policy.
The vast majority of its 67,000 US staff have supplied proof of vaccination, which was required by Monday.
"This was an incredibly difficult decision," its bosses said in a memo to employees.
The Chicago-based airline set out its Covid requirements for staff in August.
Its US employees had to upload proof of vaccination, or the first of two jabs, by the deadline on Monday.
The 593 workers who have refused a coronavirus vaccine and have not applied for an exemption on religious or medical grounds now face losing their jobs.
A further 2,000 employees have requested an exemption to the policy.
It previously said it would put those who are exempt on temporary, unpaid leave from 2 October. But those plans were put on hold after a lawsuit was filed by six employees challenging the policy.
Elsewhere in the US, few airlines have introduced vaccine mandates for its staff. Delta Airlines, for example, has announced a $200 (£148) monthly health insurance surcharge for those who are not jabbed.
Yes that’s very disappointing that only 600 out of 67,000 are willing to be fired.
What’s that verse about it easier for a camel to go through the eye of a needle than a rich man to enter the kingdom of God?
We are all rich. Even at min wage.
How many people are willing to refuse the injections? Most don’t want to give up their riches, which means they may face death instead of a glorious new earth just around the corner.
You cant take your riches with you...
All numbers are fake remember that! They report the story that way, so they make everybody feel it’s only 600 people so we might as well capitulate. I guarantee you it’s a lot more than 600 people who did not conform. And another high percentage of people who provide a fake vaccine cards. They want us to believe that people are actually doing this when they are not.