The latest security measures imposed last week followed intelligence warnings that al Qaeda's chief bomb maker, Ibrahim Hassan al-Asiri, who is thought to be based in Yemen, had linked up with jihadists in Syria to pass on his skills.
I have no doubt, from what I have learnt, that these new steps are not bureaucratic nor an overreaction.
Sadly, they are unavoidable.
It is simply foolish to believe that the threat is either minimal or now behind us.
We have, indeed, been fortunate but, sadly, this has not been because the terrorists have, since 2005, given up trying to do us harm.
As Andrew Parker, the head of MI5, has made clear, each year there have been serious plots which if they had not been identified and disrupted would have led to the deaths and mutilation of many British citizens.
– Chairman of the Intelligence and Security Committee Sir Malcolm Rifkind
Sir Malcolm Rifkind, the chairman of the Intelligence and Security Committee, who disclosed that he had been briefed in advance about the measures, said that he had been left in no doubt that they were necessary.
However, he said that he had encountered a level of complacency among some elements of the public which he found "seriously disturbing".
The head of the parliamentary committee which oversees the work of Britain's intelligence agencies has said that newly imposed airport security measures are "unavoidable".
Sir Malcolm Rifkind, the chairman of the Intelligence and Security Committee, said jihadi extremists were deploying "devilish technical skill" to create ever more sophisticated devices to evade existing security measures.
Writing in The Sunday Telegraph, he warned of the dangers of "complacency" among the public in the face of the failure of the terrorists to mount any successful mass casualty attack in the UK since the 7/7 bombings in London in 2005.
The case for a third runway at Heathrow will be submitted today by bosses of the west London airport. The three options which will be presented include:
1) A third runway to the north west of airport which would require part of the M25 being put in a tunnel and affect the villages of Longford and Harmondsworth.
Passenger capacity: 130m. Cost: £17bn. Starts: 2026. Demolishes: 950 homes
2) A third runway to the south west of the airport which starts over Wraysbury and King George VI reservoirs. A section of the M25 would need to be reconfigured and tunnelled and the village of Stanwell Moor flattened.
Passenger capacity: 130m. Cost: £18bn. Starts: 2029. Demolishes: 850 homes
3) A third runway close to Sipson, Harlington and Cranford Cross. It would be a shorter length with fewer planes, the cheapest and quickest option but also the noisiest and the highest number of homes would be affected.
Passenger capacity: 123m. Cost: £14bn. Starts: 2025. Demolishes: 2,700 homes
Air traffic control company Nats said it is restricting the number of aircraft flying across the south of England and those taking off from airports due to technical problems at its Swanwick control centre in Hampshire.
Passenger Jean Walker said some people had to jump from the aircraft wing to the ground.
It was terrifying.
We were about to take off and the plane started shuddering and there were lights flashing and smoke and the crew started shouting 'Get out, get out'.
She said two women had to jump from the aircraft's wing because there was no escape chute available to her:
We were sitting at the wing and the girl opened the door and we went out on the wing, but there wasn't a chute there.
There were about eight or 10 of us on the wing and I was saying people couldn't come out because there was no chute.
Two girls jumped off the wing on to the ground. They were OK.
Other people got hurt coming down the chutes - they were inflated, but the hostesses were just shouting 'Jump, jump' and people were just banging into each other at the bottom, and about four people were taken to hospital.