There was major disruption to air travel this afternoon as airspace above London was closed. A glitch at the state-of-the-art UK air traffic control centre headquarters in Swanwick, Hampshire, caused severe disruption.
Airspace has now reopened, but passengers are experiencing long delays.
With some people stuck in airports and others in planes circling London's airports, there was plenty of activity on Twitter from bored and frustrated passengers.
Here are some of the best tweets from this afternoon:
Stuck in Dublin airport due to air traffic control problems, don't know what to do with myself ha ha #kammyselfie pic.twitter.com/uxehUGyHRG
— Chris Kamara (@chris_kammy) December 12, 2014
Was in #Heathrow earlier, fiddling with Amy's MacBook. Clicked on a thing that said *Turn Airport off*. Am now in custody.
— Annie West (@anniewestdotcom) December 12, 2014
Unbelievable view of #Heathrow Airport on a Friday afternoon. No aircraft departing. London airspace closed pic.twitter.com/wj2OFtGbgi
— Jonny Hallam (@Jonny_Hallam) December 12, 2014
Got to admire the insouciant pilot who announced 'airspace closed' in same 'cruising at 30000 feet, enjoy the flight' voice
— Alastair Campbell (@campbellclaret) December 12, 2014
Britain putting its top technicians to work to get its airspace open again. pic.twitter.com/Fu9x4jU0Tq
— Dave Itzkoff (@ditzkoff) December 12, 2014
Upside of air traffic chaos: circling #london snapped this b4 landing @ #heathrow. Flight fr #LA delayed just 1 hour pic.twitter.com/iOJUftPhSw
— Jack Garland (@jackwgarland) December 12, 2014
Stuck on the runway at Heathrow en route to Berlin... but we have beer! And it's Christmas! @BBCLondonNews #Heathrow pic.twitter.com/cES0EHPuCo
— Phil Damerell (@Phil_Damerell) December 12, 2014
