US aviation chiefs launched an urgent investigation today after two passenger jets were said to have come within 100 feet of each other on a runway at Los Angeles International Airport.
Federal Aviation Administration spokesman Ian Gregor said radar data was being analysed to determine the planes' exact distance.
The so-called runway incursion involved a Midwest Express Embraer 190 that landed and taxied towards a runway on which a Northwest Airlines Boeing 757 was taking off for Honolulu on Sunday afternoon.
Midwest Express Flight 1503, arriving from Milwaukee, landed on the airport's southernmost runway and was told to turn on to a taxiway and hold there.
Mr Gregor said the jet was supposed to stop 200 feet from the edge of a parallel runway but continued on. A controller saw what was happening and ordered the aircraft to halt.
Los Angeles International Airport has four parallel runways, two on the north side of the central terminal area and two on the south side. Planes landing on the outer runways have to cross the inner runways to reach the terminals.