Airlines have been ordered to replace or modify the cockpit display units fitted to hundreds of Boeing jets to avoid signal interference.
US regulator Federal Aviation Administration (FAA) said tests had indicated that mobile phone and computer signals could cause the screens to go blank. The affected planes are typically fitted with several screens, each of which costs thousands of dollars. Honeywell – the displays’ manufacturer – has stressed that the problem has not been experienced in-flight.
“The only known occurrence was during a developmental test conducted on the ground,” said spokesman Steve Brecken.
“We worked with Boeing and addressed any concerns in 2012 with new display hardware.”
Boeing had previously issued an alert in November 2012 after an aeroplane operator and wi-fi vendor noticed interference caused by the installation of an in-flight internet system. The “phase 3” display units were found to be susceptible to the same radio frequencies used to transmit data via wi-fi.
In addition, the FAA said it was concerned that the screens could be disrupted by mobile satellite communications, cellular signals from phones, and air surveillance and weather radar.
The watchdog noted that the displays were required to provide pilots with information about airspeed, altitude, heading and pitch and roll, and added that the fault could cause a crash.
“We are issuing this AD [airworthiness directive] to prevent loss of flight-critical information displayed to the flight crew during a critical phase of flight, such as an approach or take-off, which could result in loss of airplane control at an altitude insufficient for recovery, or controlled flight into terrain,” it said.
Several airlines have opposed the directive saying the signals from gadgets were not strong enough to cause disruption.