They did, however, give clearance to people who must have had good reason to believe that they should be wanted.

When he could not fix the brakes, the pupils, aged 12 to 17, were finally evacuated at 5.12am - although safety chiefs had not given clearance.

Criminals wrongly given clearance would hardlycomplain.

Half an hour later, after inspection by the airport's engineers, the plane was given clearance for another take-off attempt.

Incoming aircraft not given clearance to land, however, will go into a holding pattern and wait until given clearance.