At Heathrow's Terminal 5, the queue to re-book cancelled flights with British Airways stretches almost the entire length of the terminal building.
One family, about three-quarters of the way up, said they had already been waiting an hour and a half.
They were due to fly to Frankfurt this morning but their flight was cancelled. They don't know whether they may be able to get on a flight tonight or have to wait until tomorrow morning.
Airport staff are moving through the queue handing out bottles of water.
Despite the disruption, and the huge number of frustrated passengers waiting for news, there is a surprising calm in the terminal as people wait patiently to discover if and when they will be able to leave.
More top news
As the polls close in the Scottish referendum, we look at who won the war on social media - the Yes campaign or the No campaign?
How do you break apart a Union of countries? If Scotland has just voted Yes that will be a problem for politicians both sides of the border.
CCTV footage has captured the moment an "optimistic" thief failed to steal a large piece of art by hiding it underneath his hoodie.