Air traffic controllers at O'Hare International Airport are losing track of planes and seeing phantom images on radar screens, possibly because of stray signals from a new safety system, a federal official said.
Images appear and disappear usually for 15 to 20 seconds, distracting controllers but not long enough to jeopardize safety, Jim Dermody, spokesman for the Federal Aviation Administration, said Wednesday.No similar incidents have been reported at other airports, he said.
Dermody said the malfunctions are unrelated to three near-collisions reported during the past month in the Chicago area.
The FAA suspects the problem is caused by a new cockpit computer system - Traffic Alert and Collision Avoidance System, or T-CAS - that alerts pilots to approaching planes, Dermody said.
It was installed in some planes about eight months ago and may be sending out too many electronic signals, he said.
Controllers criticized T-CAS in April when a United Airlines pilot reported seeing a phantom image on his cockpit computer near O'Hare. The FAA blamed the incident on a software problem that Dermody said has been corrected.
Dermody could not estimate how many of the malfunctions have been reported.