2 Planes Nearly Collide; Computer System Blamed

Two planes flying about 30 miles southwest of here nearly collided after an apparent computer malfunction, the Federal Aviation Administration said Saturday.

The FAA is investigating Tuesday night’s incident, which occurred at 22,500 feet, agency spokesman Fraser Jones said.

An air traffic controller in Nashua, N.H., intervened to prevent a Northwest Airlines flight with 60 aboard from possibly hitting a 21-passenger Air Ontario commuter plane, the FAA said.

The apparent failure of an in-flight computer system, known as a Traffic Collision Avoidance System, is under investigation, the FAA spokesman said.

Jones said the two planes flew less than a mile apart horizontally, instead of the usual five miles, and 300 feet apart vertically.

The planes flew so close that they merged into one on air traffic radar scopes in Nashua, N.H.

A controller noticed the errant flight path and contacted the aircraft immediately.

“There is no question that the [Traffic Collision Avoidance System] is a very valuable feature, but no one can say for sure what happened here,” Jones said.

He added that he was not aware of any similar problems with the system in the eight years it has been in use.