While the police investigation into the alleged terror plot directed against flights from Britain continues, so does the extreme inconvenience being experienced by hundreds of thousands of aspiring passengers. There is a widespread appreciation that enhanced security measures are necessary, but immense and legitimate frustration at cancellations and delays. These are occurring at a rate that seems excessive, not least to passengers being held, sometimes for hours, outside terminal buildings. One apparent way of reducing congestion inside terminals is to lock passengers out. This has driven the leading airlines, notably BA, to issue unusual public criticism of the British Airports Authority (BAA).

It is not unreasonable to ask for patience. The nature of the threat, and that arrests had to be made earlier than anticipated, mean that strict measures at airports are required. These may well be relaxed in the next few days. Questions must then be asked about about how airports are to be equipped to meet the inevitable challenges of the future.

The present difficulties have, however, been made worse by inadequate communications. It has not been made sufficiently clear to passengers precisely what they are allowed to carry on board and where they are permitted to bring those items from. Books, for example, are, somewhat curiously, banned on flights to the US but allowed for other trips from Heathrow, provided that they are purchased after passing through security. At smaller, typically short-haul, airports, reading matter brought from home is not deemed a danger. BAA should by now have clarified the position.

What may, and may not, be carried in a clear plastic bag is only part of the problem. The principal cause of delays is the understandable demand that passengers are subjected to a full body search rather than waved through if they do not set off a metal detector. On this matter, BA and Ryanair, among others, have a wholly valid point when they ask that army reservists, community support officers, private firms or retired airport security workers should be asked to assist existing staff. It is extraordinary that BAA has no adequate staff contingency plans for emergency periods that have become a part of modern life.

Staff policing Heathrow doors yesterday were hopelessly ill-informed and were seemingly unable to communicate what little information they did have to the huddled masses. The Department for Transport should satisfy itself that BAA has learnt from these mistakes — the company moved quickly to safeguard duty-free sales, but has been far too slow to ease the burden on passengers.

Ministers should also be as frank as they can be about their longer-term thinking. It would not be viewed as an outrage if items that could be converted into detonators — laptop computers, mobile telephones, iPods and cameras — were banished from hand luggage. But the public must be treated like adults, and the new rules must be clearly explained. That process needs to start now at Heathrow.