BBC News - Katy Austin & Sam Hancock
The flight chaos caused by a data processing glitch should not happen again, the head of National Air Traffic Services (Nats) has said.
Martin Rolfe told the BBC that measures were in place to protect against the "incredibly rare" system failure which has left hundreds of flights cancelled.
"If that happens again, we can resolve it very, very quickly," he said.
Nats controls most aircraft in UK airspace and receives millions of flight plans every year. Airlines submit every flight path to the national control centre and these should automatically be shared with Nats controllers.
But on Monday, Nats received data that it could not process.
Mr Rolfe said the system was designed to "fail safely" if this happened, to make sure erroneous information could not be passed on to air traffic controllers.
This caused Nats to revert to a manual system - meaning fewer flights could be handled. For several hours they had to manually input flight routes, rather than it happen automatically, which was slower and caused a huge backlog.
The incident will be investigated by the Civil Aviation Authority (CAA). Nats has confirmed there were no signs the failure was caused by a cyber-attack.