A government and industry panel has recommended that the FAA loosen its ban on using e-readers, tablets, smartphones and other electronic devices in the passenger cabin below 10,000 ft. Though the specifics have not been made public, the recommendations broadly call for allowing the use of personal electronic devices (PED) at all altitudes, except for heavy PEDs, like laptops, that could become projectiles during a rapid acceleration or deceleration. Smartphones, when not in “flight mode,” would continue to be banned inflight, as the transmissions to the ground networks are controlled by the Federal Communications Commission, but Wi-Fi connections to onboard systems could be used at all altitudes.

How the FAA will respond to the recommendations is unclear, though comments received from airlines and industry groups to the agency's August 2012 open request for solutions reveal safety tradeoffs the FAA will consider. Comments indicate an “extremely remote” chance of interference with aircraft systems based on in-service experience.

The 10,000-ft. ban on all devices, and requirements that cell phones only be used in “flight mode” at any altitude, are largely in place today to prevent PEDs—particularly ones that transmit radio-frequency (RF) energy over Wi-Fi, Bluetooth and other cellular modes—from producing RF signals that could interfere with cockpit display systems, and to keep unshielded or extensive wire cables from running through the aircraft. Avionics-maker Honeywell's position is that the effects from PEDs could vary based on whether the aircraft is built of metal or composites. “Threat levels have increased with composite aircraft due to lower shield attenuation of aircraft skin requiring increased electromagnetic compatibility protection in avionics equipment,” the company states.

Airlines have the ultimate say on use of PEDs onboard, though the FAA requires testing and analysis to prove the usage is problem-free, an increasingly difficult task given the variety of PEDs and aircraft systems to consider.

“Traditionally, airlines have used onboard testing to confirm inflight Wi-Fi systems, and ground usage of cell phones have not interfered with aircraft systems,” says Kirk Thornburg, managing director of aviation safety assurance for Delta Air Lines. “However, continued reliance on testing of every PED against every potential aircraft system is an untenable task.” Thornburg was chairman of the PED aviation rulemaking committee (ARC), launched by the FAA in January that comprised 28 government and industry representatives. The ARC presented its final report to the FAA Sept. 30. Thornburg, in his comments, suggested using a safety management system approach to the problem, which would recognize that interference is unlikely, but would provide pilots procedures to deal with any avionics issues that crop up.

The growing call to allow some PEDs to remain on below 10,000 ft. is that there is little to no empirical data that show interference problems.

Delta says a review of its maintenance defect and pilot Aviation Safety Action Program (ASAP) reports, culled from 2.3 million flights from January 2010 to October 2012, yielded 24 maintenance-defect reports and three ASAP reports where pilots cited PEDs as a potential source of an observed flight equipment discrepancy. Mechanics mentioned the possibility of PED interference when resolving avionics system problem reports, but in every case, there was no conclusive evidence.

Airbus says it has run tests transmitting PEDs (T-PED) on more than 100 aircraft, with no adverse results. “Experience shows that T-PED signals may only influence electronic parts in close vicinity to the signal source,” the airframer wrote in response to the FAA August 2012 call for solutions. “The number of active T-PEDs can be neglected; the one T-PED nearby is the highest threat. Taking this into account, an expanding use of PED does not change the situation we experience today.”