Cancelled and delayed flights caused severe disruption at Luton Airport as security measures were stepped up across the UK on Thursday.
A spokesman for the airport said there had been delays on most flights.
Easyjet cancelled all 45 flights out of Luton on Thursday. A company spokeswoman said the airline would assess the situation on Friday.
Passengers were warned that they would be searched and all, but essential items must be checked in.
About 11,000 passengers had been expected through the Bedfordshire airport on Thursday.
In a statement Easyjet said: "As a result of the severe congestion caused by increased security checks at all UK airports today, Easyjet regrets to announce that all flights from London Gatwick, Luton and Stansted are cancelled for the rest of the today."
A number of flights inbound to Luton have also been cancelled.
Passenger Andrew Layton, 40, from Hertfordshire, said: "I was supposed to be flying to Edinburgh with my wife and two children for a wedding.
"Easyjet have cancelled the flight and we are going to have to drive up now."
Lucia Harris, 74, whose flight to Nice was cancelled, said: "It is better to be safe than sorry. I think it is fair what they are doing. They have got to check things out."
The security moves follow reports that a plot to blow up planes from the UK to the US has been foiled.
Security at all airports in the UK has been tightened after MI5 raised the UK terror threat level to critical - the highest possible.