Britain's largest airport Heathrow was hit by a runway lighting failure on Wednesday morning (07.11.18).
Passengers have been advised to check before they fly as engineers work on the technical issue affecting some flights out of the airport in Greater London.
They said they expect to experience some delays due to the glitch and apologised for any inconvenience caused.
A spokesperson said: "Our engineering teams are investigating a technical issue with the lighting system for the airport's runways.
"We have activated our contingency plans and both runways are currently open and operational, although we anticipate there will be some delays at the airport "throughout this morning.
"For the latest information, passengers should check their flight status with their airlines before travelling to the airport.
"We apologise for any impact this might have on our passengers."