Subject: [NEXTEL-1] Why Your Gadgets Won't Crash the Plane

From: Marcelrf <[email-masked]>
Date: Wed, 31 Mar 2004 19:07:23 -0500

Why Your Gadgets Won't Crash the Plane

It's been called the second leading cause of air rage: flight attendants
confiscating personal electronic devices for misuse aloft.  Passengers
have good reason to be pissed. It turns out that the government and the
airlines have concocted a patchwork of contradictory and half-scientific
rules to restrict electronics in flight.  Their big fear?
Electromagnetic radiation emitted by all electronics messes with
navigation equipment, interfering with compasses, radio beacons, and
more. But there's scant evidence gizmos do any such thing. The FAA
commissioned a study to find out; the results are due this summer.
Meanwhile, here's a look at what we know.

Laptops/PDAsLaptop clock speeds exceed 1GHz; PDAs run at about half
that. The PalmOne Tungsten T3, for example, has a 400-MHz processor.The
RiskComputer chips emit radio noise in bands shared by avionics
equipment, which typically operates at108-118 MHz, 328-335 MHz, and
frequencies over 1 GHz.The RealityLaptops are the devices
most frequently cited for causing interference, but how big a problem
can they be?
They're permitted in flight above 10,000 feet, as are nontransmitting
PDAs.

Two-Way RadiosModels
popular with hikers and skiers
(such as the Motorola
Talkabout) operate in many
parts of the spectrum up to
about 1 GHz.The RiskThe UK's
Civil Aviation Authority
concluded that two-way radios
present an "unacceptable
interference risk."The
RealityApparently, they're

acceptable. Neither the FAA nor the airlines have specific rules
governing two-way radios.

Handheld GamesNintendo's Game Boy and similar gadgets have processor
speeds of around 16 MHz.The RiskThe operating frequency of these devices
is well below the range of aircraft systems. Still, since a Game Boy
isn't held to the same shielding standards as a laptop, it may be more
leaky. The RealityAnecdotal reports have linked handhelds to navigation
and communication problems, but where's the proof? The effects have
never been replicated in the lab.

Portable CD and MP3 PlayersPortable CD players operate at speeds of 28
MHz; MP3 players generally use 65-MHz to 133-MHz chips.The RiskMany of
these devices operate well outside the frequency ranges of typical
avionics, but they can radiate at multiples of their primary clock
speeds.The RealityFAA rules are wildly inconsistent - and they don't
apply to most other devices that put out potential interference (such as
pacemakers, shavers, and hearing aids).

Cell PhonesDepending on the system (GSM, TDMA, et cetera), cell phones
transmit in the 900-MHz to 1.8-GHz frequency bands at a maximum strength
of 1 to 5 watts.The RiskEven in standby mode, cells transmit
periodically to register with the network. The RealityThe ban on
in-flight cell use stems in part from the FCC, which worries about
interference with ground systems. The airlines are worried, too, but do
little to ensure phones are turned off - and often allow their use while
taxiing.
Wi-Fi and BluetoothThese wireless technologies, which operate on the
unlicensed 2.4-GHz band of the spectrum, are becoming standard in many
electronic devices.The RiskUnknown. The FAA recently commissioned an
advisory committee to look into the dangers of these and other emerging
technologies.The RealityFlight crews are winging it.  Some ban all
Bluetooth communications.

- Matthew Yeomans

http://www.wired.com/wired/archive/12.04/start.html?pg=12

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