As in the previous incident, collision avoidance equipment, which British aviation authorities have refused to make airlines install, helped to avert a potential disaster. The incident is bound to increase pressure on the Civil Aviation Authority to make the equipment mandatory, as it will be in the US from the end of this year.
Monday night's incident involved a Britannia Airways Boeing 767 leaving Palma, Majorca, with 284 passengers and crew. It was mistakenly cleared through the flight level of an inbound Air 2000 Boeing 757 with 242 people on board by Spanish air traffic controllers. As the Britannia jet, flight 219B heading for Gatwick, approached 10,000 feet, the height of the Air 2000 jet, flight 272 from Manchester, the voice from its traffic collision avoidance system (TCAS) warned the crew to abort the climb.
They did so and only then the air traffic controller, realising his mistake, told them to stop climbing. The pilot reportedly replied: 'It's too late mate, we've just missed them.' An aviation source said the aircraft were 400 feet apart.
A spokesman for Britannia Airways said: 'Our aircraft had to abort its climb. We don't know how close the planes were to each other.'
In the previous incident, reported exclusively in this week's Independent on Sunday, two holiday jets flying to Malaga in southern Spain on 3 September came within 300 feet of each other and again the TCAS came into use.
Many larger British jets such as 757s and 767s are being fitted with the TCAS equipment - which costs about pounds 150,000 per plane to buy and install - because they are used on transatlantic flights.
The CAA has been studying collision avoidance systems for some time but has refused to make the equipment mandatory. A spokesman said: 'We are not yet sure whether the benefits in safety outweigh the risks.' The authority is worried about false warnings which could lead aircraft into, rather than out of, danger.
However, a pilot who was close to Monday's incident said: 'The CAA has got to stop sitting on the fence on this issue. The sooner all planes are fitted with TCAS the better, before there is an accident. False warnings are not likely to cause a crash.'
The Spanish civil aviation authorities are investigating the