American Airlines Flight 490 nearly collided with three military F-15 jet fighters over the skies of Oklahoma Tuesday.
But a disaster was averted when the commercial airliner's on-board collision avoidance system warned the plane to rapidly descend to get out of the flight path of the military jets.
An informed source said initially that an FAA air traffic controller was believed to have made a mistake, but an operational error on the part of the military pilots could not yet be ruled out.
The incident happened about 3 p.m. Tuesday about 15 miles northwest of Tulsa, according to FAA spokesman Tony Molinaro.
The American Airlines MD
-80 was flying from Oklahoma City to St. Louis with 86 passengers and five crew members when the captain reported that the plane's Traffic Alert and Collision Avoidance System (TCAS) warned the plane of heavy traffic in the area, according to American Airlines spokesman Julia Bishop-Cross.
Bishop-Cross said a short time later the system ordered the cockpit to make an immediate descent.
The military F-15s were on their way to Tinker Air Force Base, according to the FAA.
The plane landed at its destination, and four people were taken to the hospital, including a passenger not wearing a seat belt and three flight attendants who were standing at the time of the incident and hit their heads on the cabin ceiling.
Most commercial airplanes are equipped with the TCAS system, which works independently of air traffic control to warn planes of possible midair collisions.
Typically, air traffic controllers would be alerted to military planes in their region and would be responsible for directing them away from commercial air traffic, the FAA said.