Passengers on flights to London's Heathrow Airport were delayed due to runway lighting problems, travelers complained on Twitter Wednesday.
One traveler @TomPodolec said his flight at John F. Kennedy International Airport in New York had to return to the gate after reaching the runway.
Tweet: Passengers on British Airways flights in New York, Seattle and Boston being told their flights can not depart due to issues at London Heathrow Airport; possibly runway lighting problem. #BA116 at JFK returned to gate after reaching runway. Airborne flights seem unaffected.
Heathrow Airport confirmed there was "a technical issue with the lighting system for the airport's runways," and warned that flights may be canceled or delayed in the morning.
"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," the airport said in an email to CNBC.
"We are working to fix this issue as quickly as possible," it said.
"Stuck on a @britishairways plane on runway at @JFKairport," tweeted another passenger, ShaanKhan.
Tweet: Stuck on a @britishairways plane on runway at @JFKairport because #Heathrow in complete shut down. All flights diverted. #chaos #completehysteria
"We recommend that all customers travelling with us today check ba.com before they leave home, after a Heathrow Airport lighting fault this morning caused a delay to flights from all airlines," Heathrow told CNBC via email.
"Contingency plans were quickly activated to keep the airfield open, and we plan to operate a full schedule today."
Heathrow Airport apologized to passengers in a tweet, asking travelers affected to check their flight status.
Tweet: We're currently investigating and working to fix a technical issue with the lighting system for the runways. Please check your flight status with your airlines before travelling to the airport: https://bit.ly/2zhmMco . We're sorry for the impact this will have on our passengers.
Heathrow is Europe's busiest airport, with a daily average of 213,668 passengers in 2017. The number of passengers that came through Heathrow last year came up to 78 million, according to the airport.
The airport services 81 airlines and 204 destinations in 85 countries. New York's JFK Airport is one of its most popular destinations, Heathrow's website said.