Why you can’t use a cellphone on a plane or in a hospital

It takes a plane just a handful of minutes to take off and climb to altitude, yet it’s really annoying to be told to turn off your cellphone and computer during that time. And anyway, the airline is just being fussy, right? How can one cellphone hurt a big plane? Unfortunately, it turns out flight attendants have technically sound reasons for inconveniencing you. And they’re basically the same reasons that require you to disconnect from Facebook while in a hospital’s emergency ward.

The prime offenders are Transmitting Portable Electronic Devices (TPEDs) such as cellphones, smartphones and iPads, all of which use high-frequency short-wave radio transmitters and receivers like Wi-Fi to send or receive information.

In both airplanes and health-care facilities, electromagnetic interference (EMI) can occur when wireless devices interfere with the smooth operation of avionics, two-way radio telemetry or stand-alone electronic equipment.

In the air

To date, there is no proof that a plane has ever crashed due to interference from the radio energy transmitted by your laptop. But that doesn’t mean Transport Canada, the ultimate authority on the issue, is going to let you surf uninterrupted.

According to Maryse Durette, senior advisor with Transport Canada, TPEDs carried by passengers “have different power levels and may use different frequencies, so their effects are difficult to assess given that they are not maintained and controlled using aviation safety standards.”

Durette notes that, in 2008, interference tests carried out on TPEDs in the United Kingdom revealed “various adverse effects” on equipment performance. These included:

> inaccurate compass readings
> instability of cockpit indicators
> reduced sensitivity of instrument landing system equipment
> background noise on audio outputs.

Current Transport Canada regulations prohibit the use of TPEDs in phases of flight during which the devices have the potential to interfere with aircraft navigation and/or communications. Their use, she said, is permitted only during the “taxi-in” phase of a flight, when the plane has landed and is moving toward the gate.

According to Robert Palmer, spokesperson for WestJet, once flights have reached cruising altitude, only devices “that do not send and/or receive are allowed to be used.” So an iPhone is okay as long as “Airplane Mode” is turned on.

Durette said Air Canada is currently conducting trials on the impact of Wi-Fi technology on two Airbus 319 aircraft. “The result of this trial will help the department assess potential regulatory changes to the existing rules.”

At the hospital

Health-care professionals have been enthusiastic adopters of wireless devices for more than 60 years, when the first pagers were invented specifically for their needs, and continuously look for technological advances in treatment and patient care.

“Generally speaking, wireless plays a huge role in the medical profession,” said Mark Choma of the Canadian Wireless Telecommunications Association. Provisions against the use of TPEDs in hospitals, he said, exist because “in prior years there was always a fear of any interference with sensitive medical equipment, usually older equipment that had not been shielded.” This is why people with pacemakers were warned to stay away from microwave ovens, for example.

According to Lars Huebner, supervisor of the Interventional Radiology Department at Royal Columbian Hospital in New Westminster, B.C., the medical equipment in his facility is now well fortified against EMI. Visitors to Royal Columbian are not prevented from using voice or data applications. “In fact, our physicians, including surgeons in operating rooms, often use them to consult with one another to help provide the best in patient care.”

Although shielding seems to have done away with the technical concerns around TPEDs, Choma said the need for patient privacy may still result in some restrictions, particularly in areas where chatty cellphone users might disturb critically ill patients.

And on that same note, Huebner recommends against calling your spouse during your own angioplasty. “It is advised that you not use your cellphone while having a procedure done.”

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