Travellers have endured a fifth day of delays and cancellations at several UK airports despite the country's security threat being downgraded to "severe".
Air passengers are still facing delays and cancellations
The hand luggage ban has been relaxed, but will not come into force at parts of Heathrow or Gatwick until Tuesday.
Some airlines have criticised operator BAA over the delays that has created.
Meanwhile, police investigating the suspected plot to blow up transatlantic flights have found a handgun and a rifle in woods at High Wycombe.
Twenty-three people are in custody in connection with the suspected plot.
The detentions of all of them will now be reviewed by a district judge on Wednesday, after Scotland Yard was given permission to hold a 23rd person beyond Monday.
The UK security threat level was raised to "critical" last week amid fears of a plot. The order for it to be downgraded, meaning an attack is now considered highly likely but not imminent, came from Home Secretary John Reid early on Monday.
It meant new rules allowing passengers to take one item of small hand luggage onto planes.
Most airports around Britain, including Birmingham, Belfast, Cardiff, Glasgow, Edinburgh and Luton, have implemented the new hand luggage rules.
Most of the delays and cancellations took place at London's Heathrow and Gatwick, with the majority of flights to Scotland being cancelled.
But BAA said the relaxed rules would not be implemented across Heathrow and Gatwick until 0430 BST on Tuesday, although domestic passengers using Heathrow's Terminal 1 have been checked in under the new guidelines since 1500 BST.
It is thought that security remains tightest around flights leaving the UK for the US.
At Heathrow Airport 68 flights were cancelled on Monday, while 27 flights from Gatwick were cancelled, including all British Airways domestic flights, and 15 at Stansted.
Heathrow's operator BAA warned passengers to be prepared for delays.
But a spokesman added that a reduction in searches of passengers from 100% on Thursday to 50% had already "improved flow" through the airport.
There would be "some degree of normality" coming back to Heathrow, he said, and BAA would be working with the government and others to "make this approach more sustainable".
First Choice Holidays, while welcoming the relaxation in restrictions, said it was "disappointed our customers have had to queue and suffer because of a lack of resources".
Thomas Cook Airlines said it was asking passengers not take hand luggage for the rest of the week.
BAA chief executive Stephen Nelson said the current situation was "the biggest security crisis in aviation history in this country".
But he expected BAA's airports to be on "an improving trend" over the next two days and said extra staff had been brought in.
"We have brought in as many people as we can in terms of those who are on holiday, those who are prepared to volunteer," he said.
Extra airline staff had been called in to Heathrow - some from as far as Australia - and were handing out umbrellas to those waiting outside on Monday.
At Manchester Airport, where the new luggage regime is in place, a spokesman said the limit of one piece of hand luggage was being strictly enforced.
"It would help us if passengers don't over-pack hand luggage," he said.
He said the new procedures were "running smoothly" and there were no delays or cancellations on flights.
Liverpool's John Lennon Airport, Leeds Bradford International Airport and Robin Hood Airport near Doncaster were also among others to introduce the new guidelines and were not experiencing delays.