The British Airways IT crash which has caused unprecedented disruption for the airline could last for several days, experts say.
Thousands of holidaymakers were stranded after BA flights from Heathrow and Gatwick were grounded on Saturday.
It is feared that it could take days for services to return to normal and clear the backlog of passengers.
Air industry consultant John Strickland said: "There's a massive knock-on effect.
"Customers and from the airline's point of view - manpower, dealing with the backlog of aircraft out of position, parking spaces for the aircraft - it's a challenge and a choreographic nightmare."
He added that the problems with BA's IT systems last year were not on the scale of this issue.
"They were bedding in a new check-in system last year and there were teething problem but not of the magnitude of this," Strickland said.
The disruption has been compounded by the timing of the outage coinciding with a bank holiday weekend and school half-term holidays.