NEW safety software is to be installed at a Hampshire air traffic centre after a controller sent two passenger planes on a collision course.

A mix-up at the Swanwick centre led to a Virgin Atlantic Boeing 747 jumbo jet and a Delta Airlines Boeing 767 almost crashing over Wales - putting hundreds of lives in danger.

It was only when a cockpit collision avoidance system sounded, that the Virgin pilot took evasive action and climbed so steeply that a female passenger was thrown off balance and broke an ankle.

The Hampshire-based controller thought he was directing the two planes apart - but in fact he was bringing them dangerously closer.

When he radioed to the Delta pilot to turn, the worried pilot, bound for Brussels, replied: "Negative. I'd turn into him."

The Virgin pilot, flying from Heathrow to New York, assessed the risk of a collision with the Boeing 767 as "high".

At one point, the Virgin plane was just 100ft above the 767 and separated laterally by 1.8 nautical miles - breaching the legal minimum between aircraft.

The incident occurred when a controller mistakenly transposed identifying data on the positions of the two aircraft. As he tried to guide them apart, the closer they came.

A crowd gathered around the controller's screen as the aircraft converged, in November 2002.

A spokesman for National Air Traffic Service (NATS) said: "Changes to the software at Swanwick will be made next month after an extensive testing programme.

"This work began immediately after the incident, and the CAA's Safety Regulation Group (SRG) was present at selected periods during a series of trials last April.

"Following the incident, a revised operating procedure was put in place to prevent this incident recurring."

Although their own pilot said there was a high risk of collision, Virgin played down the incident.

A spokesman for the airline said: "We are extremely satisfied with the safety system in place. The two aircraft came closer than they should have but safety systems worked as they should do."

Delta declined to comment. Officials from the Prospect union which represents staff at Swanwick were unavailable for comment.