1 Although rare, air crashes do happen. Predominantly, the reason for this is human failure such as pilot fatigue. One kind of accident, which is known as ‘controlled flight into terrain’, where the aircraft appears to be under control and yet still flies into the ground, has a chance of happening less than once in 2 million flights. To occur, a whole chain of minor failures must happen. The pilot at the controls has to be flying at the wrong altitude (one chance in a thousand). The co-pilot would have to fail to cross-check the altitude (one chance in a hundred). The air traffic controllers would have to miss the fact that the plane was at the wrong altitude (one-in-ten chance). Finally, the pilot would have to ignore the ground proximity warning alarm in the aircraft (which can be prone to give false alarms, a one-in-two chance).

(a) What are your views on the quoted probabilities of each failure described above occurring?

(b) How would you try to prevent these failures occurring?

(c) I f the probability of each failure occurring could be reduced by a half, what would be the effect on the likelihood of this type of crash occurring?