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Aircraft and 'Portable Electronic Devices'
by Elonka at 8:46 am EDT, Sep 15, 2003

] On another occasion in 1996, a Boeing 767 pitched and
] dropped 120 metres before pilots recovered control. A
] passenger using an electronic dictionary was asked to
] turn it off, and the plane's systems returned to normal.
. . .
] Pilots routinely ask for portable devices to be switched off
] during take-off and landing. because they are too busy to deal
] with problems with interference. But, once in the air, when
] passengers are allowed to switch devices on, pilots have had
] to contend with a range of bewildering malfunctions.

This is a subject I've often been curious about, since I routinely use my Palm Pilot on aircraft. Does this mean that each time that I'm in seat 27C and I flip open my Palm IIIc, that the aircraft's autopilot goes "hmm"? I'd always thought that the signal from anything so small would be inconsequential, or no worse than my seat-mate's digital calculator sports watch (which can't be turned off), and that the main danger was from things such as cellphones or larger devices such as laptop computers.

Now I'm not so sure . . .

RE: Aircraft and 'Portable Electronic Devices'
by Decius at 11:53 am EDT, Sep 15, 2003

Elonka wrote:
] This is a subject I've often been curious about, since I
] routinely use my Palm Pilot on aircraft. Does this mean that
] each time that I'm in seat 27C and I flip open my Palm IIIc,
] that the aircraft's autopilot goes "hmm"? I'd always thought
] that the signal from anything so small would be
] inconsequential, or no worse than my seat-mate's digital
] calculator sports watch (which can't be turned off), and that
] the main danger was from things such as cellphones or larger
] devices such as laptop computers.
]
] Now I'm not so sure . . .

Its really hard to say. To be sure, these devices produce signals which can cause interference. Its not really a function of size, per say. For digital devices its a function of frequency, power, and sheilding. Your palm pilot has a lot more power at a much higher frequency then a watch. It also has better sheilding. Keep in mind that complex devices like palm pilots may also have analog components that bleed RF.

Next time you are hanging around a bunch of hackers, find one with a frequency scanner. Scan the range around the clock speed of a nearby desktop computer. Desktops have very poor sheilding. You will pick up a strong signal near the clock speed.

Having said that, if these things really crashed planes they would need to be a lot more paranoid then they are. Devices like these are powered up on planes all the time, either intentionally or by accident. I was once on a flight with a passenger who left his cellphone on the whole time and frequently checked it when he was sure the flight attendents weren't looking. I've also had friends receive calls in the air when they had forgotted turn their phones off.

RF interference is an easy excuse that airlines can claim when there are problems that were actually caused by human error. It is difficult for investigators to prove otherwise. Furthermore, it allows airlines to sell their own phone and (soon) internet services. I think its probably more likely that Austrailia has a little problem with their aviation administration failing to investigate claims of RF interference, and this is more of a subtle cry for more complete investigations then a real alarm about passenger use of electronics.