From the BBC..
Simon Calder, travel editor for The Independent, estimates that 15,000 travellers and 100 flights - to and from Stansted - were affected by Friday's cancellations.
He told the BBC the problems stemmed from a decision to move people from the smoke-filled check-in area to the air-side zone beyond security.
"As a result of that, because they hadn't been screened - because they were taken there in a hurry - no flights could depart until everyone was re-screened and the air-side area had been swept by security services to make sure no passengers had stayed behind."
He said the whole process took so long that by 20:00 BST the airport and airlines agreed to shut down for the rest of the evening in the hope of minimising the impact on the following day's flights.