update It's official: using Wi-Fi on a plane can interfere with a pilot's navigational equipment, according to a statement from airline equipment manufacturers Honeywell Avionics and Boeing today.
According to a report first published by US aviation site Flightglobal, Honeywell Avionics has confirmed that its Phase 3 Display Units used by pilots in Boeing 737 aircraft are susceptible to "blanking" in the presence of Wi-Fi equipment.
Boeing confirmed to ZDNet Australia this afternoon that the issue does exist, but said that it has not delivered any planes suffering the fault.
"Blanking of the Phase 3 Display Units (DUs) has been reported during airline EMI (electromagnetic interference) certification testing of wireless broadband systems (Wi-Fi) on various Next-Generation 737 aeroplanes," Boeing told ZDNet Australia in a statement.
"Boeing has deferred the activation of wireless systems that interface with passenger devices that could potentially interfere with the DU 3 displays," it added.
"Honeywell has assured us that they are working to address the problem and we are satisfied that they are taking the necessary steps to do so."
A senior Boeing engineer stressed to ZDNet Australia that the levels of EMI required to affect a pilot's screen exceeds the levels produced by the normal operation of normal levels of Wi-Fi use.
"Boeing and Honeywell have concluded that actual EMI levels experienced during a flight where there is normal operation of a Wi-Fi system will not cause any blanking of a Phase 3 display. This is not a safety issue with currently operating 737s and 777s," a Boeing engineer said.
Screens that blanked during testing restored themselves within an acceptable time frame during testing, said Honeywell Avionics in a statement, and posed no risk to aircraft operations.
"The screens reappeared well within Boeing's specified recovery time frame. The screens have not blanked in flight and are not a safety of flight issue. Honeywell is working to ensure the problem is addressed and fixed and that our technology will continue to exceed specifications," Honeywell said.
While cabin crew do instruct passengers to power down Wi-Fi devices for the entirety of flights around the world, some US-based carriers install Wi-Fi equipment into their aircraft for passenger use.
ZDNet Australia contacted Jetstar, Virgin Blue and Qantas regarding the issue. Only Jetstar responded at the time of publication, saying that it didn't use the equipment susceptible to the fault.
Updated at 10:27am, 11 March 2011: added additional comment from Boeing.