Passengers at Birmingham International Airport and Coventry Airport were hit by delays when security was tightened following a terror alert.
Armed police are still at Birmingham International Airport, where all vehicles except buses and taxis are being diverted from terminal buildings.
Coventry Airport has brought in extra staff to ensure flights leave on time.
Two people were arrested in Birmingham as well as a number in London and High Wycombe, Bucks, in the alert.
Security was tightened across the country after MI5 raised the terror threat level to critical - the highest possible.
Scotland Yard said a terrorist plot to blow up planes in mid-flight from the UK to the US has been disrupted.
It is thought the plan was to detonate explosive devices smuggled on board in hand luggage.
West Midlands Police said the two men were arrested under the Terrorism Act and were in custody.
'No specific threat'
Officers were searching two properties in Birmingham.
A premises in Belchers Lane, Bordesley Green, has been sealed off and a second property in St Margaret's Road in Ward End was being searched.
Police said there was no specific threat to the West Midlands.
At Birmingham Airport's passenger concourse, hundreds of passengers had to transfer essential items for hand luggage into clear plastic bags provided.
A spokeswoman for the airport said on Thursday morning they were experiencing delays of up to one-and-half hours.
She said there had been few cancellations, mainly among low-cost carriers.
"It is pretty much like a busy day but we seem to be catching up with ourselves."
She said passengers should arrive for flights earlier as it is taking longer for passengers to check-in and go through security checks.
Earlier Pete Farrant, on his way to the US with his family, described the scene as "chaos".
He told BBC News: "There was no communication, nobody was talking to us. I was having to relay to people at the back what was happening.
"I understand about security but I just think you've got to be a bit lenient.
"If something's going to happen, it's going to happen."
However other passengers accepted the need for tighter security.
Raymond Loosely said: "We had to repack a couple of our bags, that's all. They (airport staff) are taking sensible security precautions, and we're not going to give in to these people.
"It's better to be inconvenienced than put in danger."