The incident on the afternoon of 3 September involved two Boeing 757s, a Monarch Airlines plane with 235 passengers and nine crew aboard travelling from Manchester and an Ambassador Airways from Gatwick with 233 passengers and nine crew. The Monarch plane was cleared by Spanish air traffic control in Seville to descend from its cruising height of 35,000ft down to 11,000ft, but its crew was unaware that the Ambassador plane was immediately below it.
Withinseconds, the pilot was alerted by the voice of the plane's traffic collision avoidance system (TCAS), which warned him: 'Climb, climb now'. As he did so, he saw the Ambassador plane below him.
The Monarch pilot, Ken Norman, reported the incident to the Spanish civil aviation authorities, convinced that a tragedy had only been avoided by the TCAS installed in his aircraft. However, TCAS is only fitted in the Monarch plane by chance because the company uses it on charter flights to Florida; it was not fitted on the Ambassador 757 which does not fly to the United States. The equipment is being made mandatory in the US from the end of this year.
Monarch's chief pilot, Rob Wood, told the Independent on Sunday: 'The risk of collision was very high. The pilot's report reckons that the Ambassador 757 was 300ft away when they saw it. We were reluctant to install the equipment at first but this shows how important it is.'
The passengers wereunaware of any danger.
There had been one other warning, near Corfu where there was no risk of collision, and a dozen false alerts. He said: 'It's not good to get nuisance warnings but it's part of a pilot's job to cope with them. Clearly in this case, the equipment did a damn good job.'
TCAS works by radar, creating atheoretical 'bubble' ahead of the aircraft. If any other planes enter that bubble, the warning is sounded and shown on a screen.
The Civil Aviation Authority has been studying collision avoidance systems for some years but is reluctant to force airlines to introduce the system because it is worried that it can create danger by making pilots override controllers' instructions. David Harrison, theAuthority's head of collision avoidance, said:'We do not have sufficient evidence to prove conclusively that there are major safety benefits.' A CAA study of the system is expected to be completed within a year, but the authority is reluctant to impose the cost on British airlines because of competition from foreign rivals.
But one British pilot said: 'This is not the only incident where the equipment has helped avoid a disaster. It should be made mandatory in Europe, before there is a collision rather than afterwards.'Reuse content