Air travellers flying from the west coast of Scotland have been facing delays due to a major security alert.
Only passengers with tickets are allowed in the terminal building
At Glasgow Airport, only passengers carrying flight tickets were allowed to enter the terminal building. All shops have been closed as part of the alert.
No hand luggage was being allowed on flights and passengers were warned delays were likely from all airports.
A spokesman for Prestwick Airport asked passengers to allow extra time for check-in and security searches.
He said: "Glasgow Prestwick Airport would like to reassure passengers we have acted quickly to put these new security arrangements in place and that there is no reason not to travel.
"We also apologise sincerely for any inconvenience caused.
"Unfortunately delays in processing are likely. Airport management will liaise closely with airlines as decisions on the departure times of aircraft are ultimately theirs to make."
He added: "However, our first wave of flights left this morning with only minor delays."
Brian Donohoe, MP for Central Ayrshire, praised the response to the alert.
He said: "The airport went into top gear to deal with the latest situation.
"It is a real feather in the cap for the airport's management and the police in controlling this latest development. We must all try and remain calm in these circumstances.
"I trust those who oppose the government's fight against terrorism will now consider their comments inappropriate."
The BAA website crashed due to a high level of people visiting the site for information.
All BAA airports remain open but passengers should expect delays.
By 0745 BST on Thursday, hundreds of travellers were stuck in check-in queues that stretched across the width of the Glasgow Airport terminal building.
Travellers are met by police on their arrival at Glasgow
Upstairs, as people tried to make their way to the departure lounges, the queue for security checks wound its way through the building, past the closed shops.
People arriving at Glasgow Airport were met at the doors by uniformed police officers and airport staff who checked their tickets.
They were handed a note with instructions on what they were allowed on as hand luggage and a clear plastic bag.
Two armed officers patrolled inside and outside the building.
A spokesman for Glasgow Airport said: "BAA wish to stress that these are precautionary measures.
"During the next few days airports will be extremely busy, therefore only those intending to fly should come to the airport.
"Passengers are also asked to use public transport to get to and from the airport wherever possible. "
He added: "Passengers are asked to be patient while these additional security measures are put in place. Delays are likely and passengers are therefore asked to allow extra time for their journey."