UK cockpit crew representatives are expressing alarm at the possibility that the government is prepared to withdraw from the European Union without a trade agreement.
Pilots union BALPA claims that such a decision could leave UK carrier unable to operate, and disrupt ticket sales long before the formal exit date in March 2019.
BALPA general secretary Brian Strutton says the UK aviation industry would be "devastated" by failure to reach a UK-EU agreement.
"Unlike most other sectors there are no World Trade Organisation, or any other, rules to fall back on for aviation if there is no deal," he states. "UK airlines could find they have to stop flying – it’s that serious."
UK transport secretary Chris Grayling, during a parliamentary session on 9 October, had insisted that the country's air transport industry was "very strong" despite the collapse of leisure carrier Monarch Airlines.
"We should be confident about the sector," he said.
BALPA is concerned, however, that uncertainty over a future agreement with the EU could begin affecting passenger confidence "long before" the UK's exit date.
"The entire industry has said that we have to see evidence of the post-Brexit plan for aviation now if we are to avert a catastrophic crisis of confidence," says Strutton.
"It is utter madness for anyone to think that [failure to reach a deal] would be anything but a total disaster for our world-leading UK aviation sector and beyond."