EasyJet has grounded its entire fleet of planes and said it cannot give a date for when they will restart.
The budget airline said it had made the move due to the “unprecedented travel restrictions” imposed by governments globally due to the virus pandemic.
It had already cancelled most flights but had been running rescue flights to repatriate Britons stranded abroad.
The move came as regional airline Loganair said airlines were unlikely to survive without a government bailout.
The pandemic has had a severe impact on airlines, Loganair boss Jonathan Hinkles told the BBC’s Tom Burridge.
He said that any airline saying it could survive without government help “would probably be lying”.
EasyJet said its cabin crew would be furloughed, with staff paid 80% of their wage from 1 April through the government’s job retention scheme.
The budget airline’s boss Johan Lundgren said he was “working tirelessly” to make sure the airline was “well positioned to overcome the challenges of coronavirus”.
“I am extremely proud of the way in which people across EasyJet have given their absolute best at such a challenging time,” he added.
EasyJet’s headquarters are at London Luton Airport and it has 331 planes. In normal times, it serves 159 airports and 1,051 routes.
Mr Lundgren said the airline had operated its last rescue flight on Sunday 29 March, but would continue to offer further rescue flights “as requested”.
The vast bulk of flights to and from the UK have been grounded due to travel restrictions imposed to control the spread of coronavirus, with many airlines expected to seek government help to survive.
Virgin Atlantic has already indicated that it will seek a bailout and airlines such as EasyJet are expected to follow suit.
The government has said it will only step in to help struggling airlines “as a last resort” on a case-by-case basis.
But industry group the International Air Transport Association (IATA) has warned of an “apocalypse” in the aviation sector as it urged governments around the world to help.
Loganair’s Mr Hinkles warned that the connectivity of remote Scottish islands and rural communities across the UK “cannot be maintained without air services”, arguing that government support for his airline was “essential”.
Loganair operates routes to the UK’s most remote airports such as Barra in the Outer Hebrides, where 19-seater planes land on the beach.
It is still running a higher proportion of its flights than other airlines because some travel to the most remote parts of the UK is still considered essential.
The airline is still ferrying people, mail and essential goods, such as pharmaceutical products, out to about 15 island airports.
Some of the most remote routes are subsidised by the Scottish government.
‘We have to fly’
Nevertheless, the Scottish carrier has had to ground half of its fleet and dramatically slash its flying schedule. This has put its entire operation in jeopardy.
“We can’t just shut down”, Mr Hinkles said. “Morally, we have to fly.”
‘In the national interest’
Every airline is now negotiating with leasers, hoping that they will be granted more flexibility over payments.
Aside from the immediate problem of keeping the operation going, which Mr Hinkles believes is “in the national interest”, the longer-term problem is how quickly airlines like his can recover from the crisis – whenever travel restrictions are lifted.
He says that predictions within the industry about when airlines will fully recover are bleak.
“When a hairdresser is allowed to reopen, there will be a queue of people who need a hair cut,” he says. “That won’t be the case with aviation.”
All airlines have called for additional support measures from the government to weather the storm.
The industry group Airlines UK and the Airport Operators Association have asked the government to cover air traffic control charges and payments to the Civil Aviation Authority until the end of this year.
Airlines also want a six-month suspension of the Air Passenger Duty tax, which brings in £3bn every year to the Treasury.
The boss of Loganair said the impact of the pandemic on aviation had been “fast and severe” and that continued support would be needed once the height of the crisis has passed.
In the case of his regional airline, he warned that it would be “easier to support the infrastructure which is there, rather than to try and build that infrastructure” in the future.
A spokesperson for the Department for Transport said that the aviation sector is “important to the UK economy”.
They added: “We are willing to consider the situation of individual firms, so long as all other government schemes have been explored and all commercial options exhausted, including raising capital from existing investors.”