As anyone who has flown has heard, using a cellular telephone aboard
an airplane is dangerous.

American Airlines warns passengers that cell phones "may interfere
with the aircraft's communication and navigation systems." Similar
warnings come from Delta, United and Continental. British Airways
links cellular interference to potential problems with compasses and
even cabin pressure.

What the airlines don't tell passengers is that there is no scientific
evidence to support these claims. What concerns there are about
cellular phones in airplanes dwell in the realm of anecdote and theory
 -- and to some extent in that of plain finance. There is money to be
earned or lost by cell-phone companies and airlines if cell phones are
used in-flight.

Battery of Tests

A 1996 study commissioned by the U.S. Federal Aviation Administration
looked at thousands of flight records and failed to find a single
instance in which equipment was affected by a wireless phone. The
study was conducted by RTCA Inc., a nonprofit organization that sets
industry standards for airplane electronics.

Plane makers Boeing Co. and Airbus Industrie have bombarded their
aircraft with cell-phone frequencies and discovered no interference
with communication, navigation or other systems. One likely reason
that no problems were found: cellular phones don't operate on any of
the frequencies used by airplane systems.

"The airlines are misleading the traveling public," says John Sheehan,
who headed the RTCA study and says he has often used his own cell
phone in the sky. "There is no real connection between cell-phone
frequencies and the frequencies of the navigation" or communications

Using cell phones aloft on commercial and private aircraft is banned
not by the FAA but by the Federal Communications Commission, which
regulates telephone use. In prohibiting airborne use in 1991, the FCC
was mainly concerned about cell phones' potential to interfere with
ground-to-ground cellular transmission.

The FAA has never outlawed cell-phone use in airplanes. But the agency
supports the FCC ban "for reasons of potential interference,"
according to an FAA advisory. Despite the findings of the 1996 RTCA
study, the FAA remains concerned about anecdotal evidence of
cell-phone interference in flight records, says an FAA spokeswoman.

The FAA isn't the only party still concerned. Boeing continues to
advise airlines against cell-phone use in the sky. That's because the
electrical charge from the batteries in most handsets exceeds the
plane maker's standards. Although Boeing's tests have never shown this
to be a problem, in theory the electricity emanating from the device
could create interference with airplane systems.

Economic Incentive

The airlines and telecommunications companies also have an economic
incentive to keep cell phones turned off in the air. The carriers
receive a cut of the revenues from the telephones installed onboard.
 The two main providers of this air-phone service, GTE Corp. and AT&T
Corp., charge about $6 for a one-minute call, more than 20 times
typical cell-phone rates.

These in-flight telephones also operate on cellular technology --
using a single airplane antenna to which the onboard phones are
typically wired.  AT&T and GTE, which recently agreed to sell its
Airfone service, decline to discuss air-phone financial arrangements,
as do several airlines. But Mr.  Sheehan says airlines pocket about
15% of all air-phone revenue generated on their planes. GTE declines
to discuss Airfone revenues, but analysts estimate the unit's annual
revenues at $150 million.

Some airlines also restrict cell-phone use on the ground, which isn't
covered by the FCC ban, and which the FAA leaves to the airlines'
discretion. Mr. Sheehan says he believes air carriers have resisted
allowing cell-phone use on the ground because it "detracts from the
revenue they get from the air phone."

Airlines deny this, and say the bans are for the benefit of the
passengers.  "We don't believe it's a good safety issue" to allow
normal cell phones, says Andy Plews, spokesman for UAL Corp.'s United
Airlines. "We'd like people to use the air phones."

A Sponge in the Sky

The FCC's concern about air-to-ground cellular interference is real
enough. From high in the sky, a cell phone acts like a sponge,
sucking capacity out of the cellular sites that carry calls. For
ground users, cell phones communicate by connecting to one cell site
at a time; from the air, because of the height and speed of an
aircraft, the phones often make contact with several sites at once. If
allowed, this would limit call capacity, which would mean less
revenue, says Howard Sherry, chief wireless scientist at Telcordia
Technologies Inc., formerly the research arm of the Baby Bell
telephone companies, in Morristown, N.J.

The cellular signal from the air is also especially strong, since it
is unimpeded by buildings or other ground clutter. That often means it
can jump on a frequency already in use on the ground, causing
interruptions or hang-ups. And airborne cellular calls are sometimes
free because the signal is moving so fast between cells that the
software on the ground has difficulty recording the call, says Bentley
Alexander, a senior engineer at AT&T's wireless unit.

Jailed in England

The FCC says no passengers in the U.S. have been prosecuted for
violating its regulation because airlines have diligently enforced the
ban. But Neil Whitehouse, a British oil worker, is serving a one-year
jail sentence in England for refusing to switch off his cell phone on
a 1998 British Airways flight from Spain.

Sue Redmond, a British Airways PLC spokeswoman, says Mr. Whitehouse
put the plane at risk because cellular phones can disrupt the plane's
automatic pilot, cabin-pressure controls -- and "every system that is
needed to keep that airplane safe for flying."

One expert witness at Mr. Whitehouse's trial was Daniel Hawkes, the
head of avionics systems for the Civil Aviation Authority, the British
counterpart to the FAA. In a telephone interview, Mr. Hawkes says
phones have a "potential for a problem," but he concedes that there is
no "hard evidence" of any problems. Still, he says it wouldn't be wise
to allow cell phones on airplanes because the constant chatter might
annoy other passengers. "You'd probably have more instances of air
rage," he says.

Indeed, the recent trend by some U.S. airlines to allow cell-phone use
in planes parked at the gate coincides with growing passenger
frustration with flight delays and poor service. These carriers
include Northwest Airlines Corp., United, AMR Corp.'s American and
Delta Air Lines Inc. Letting passengers chat on the ground is "good
passenger service," says Delta spokesman John Kennedy.

The Early Days

Cell phones on airplanes first became an issue in the late 1980s. At
the time, many wireless devices, including laptop computers and
audio-cassette players, were proliferating. The responsibility for
setting guidelines fell to the FCC, which has joint jurisdiction with
the FAA for regulating wireless use on aircraft. Cellular companies
were overwhelmingly opposed to allowing cell phones in the air, but
broadly supported their use in aircraft on the ground.

At first, the FAA favored banning cell phones at all times. In a 1989
letter to the FCC, the FAA warned that cell-phone use could
"significantly increase the risk to aviation safety," whether
"operated on the ground or in the air."

This position was supported by most of the major airlines. Trans World
Airlines Inc. told the FCC that allowing cell-phone use, even on the
ground, "could be a detriment to public safety."

The cell-phone companies were already on the record as being opposed
to in-flight use -- but for different reasons. In a 1988 letter to the
FCC, McCaw Cellular Communications Inc. wrote that air use could cause
"highly disruptive interference to cellular systems" because of the
"greatly increased transmitting range" that cell phones have aloft.
Nynex Mobile Communications Co. warned that air use would "likely
result in significant interference to other cellular transmission."

Debating on the Ground

As the FCC continued to mull regulations, cellular companies sought to
debunk the FAA's claims of potential cellular interference with
critical aircraft systems while the plane is on the ground. McCaw,
Motorola Inc. and Alltel Mobile Communications Inc. -- now a unit of
Alltel Corp. -- noted the absence of scientific studies to support
these claims. If cell phones do truly interfere, Alltel wrote in a
1990 letter to the FCC, "one wonders why problems have not resulted
from the widespread use of cellular telephones in airport lobbies,
parking lots and other facilities in close proximity to aircraft."
McCaw cited the wide use of walkie-talkies by airport employees and
ground crews.

In 1991, the FAA backed off on ground use, saying airlines and pilots
could use their own discretion. Later that year, the FCC passed its
regulation banning airborne cellular use. The ban didn't apply to
preinstalled air phones. As an integral part of the airplanes, those
devices had to undergo strict FAA tests before they were allowed on
planes. Those tests showed no problems. As passenger carry-ons, cell
phones have never been run through the FAA equipment-testing process.

The installed air phones also posed no problems for cell systems on
the ground. The outside aircraft antenna that carries the air-phone
calls also connects to a ground-based cellular network -- but with
cells that are spaced much farther apart to avoid multiple phone-to-
ground links.

The issue began heating up again in 1992, when Rep. Bob Carr, then a
Michigan Congressman, and vice chairman of the Transportation
Appropriations subcommittee, asked the FAA for a detailed look at
alleged cellular interference. Rep. Carr had been reprimanded by a
United flight attendant for using his cell phone while a flight to
Chicago was delayed on the ground in Detroit. Mr. Carr, a pilot, says
he regularly used his cell phone while flying on commercial planes in
the late 1980s. He says he is convinced the airline ban was, and is,
"bogus" and not founded in science. The FAA asked RTCA to look into
the issue.

'Incident Reports'

When anything goes wrong on a flight, pilots or operators are required
to file "incident reports," which are collected in a database kept by
the National Aeronautics and Space Administration. RTCA, which began
its study in 1992, sifted through a decade's worth of such incident
reports, about 70,000 in all, covering both commercial and private
flights. RTCA, formerly called the Radio Technical Commission for
Aeronautics, also was given access to confidential reports kept by
some airlines in later years.

Of 384 incidents that pilots suspected involved electronic
interference, RTCA found most were baseless or didn't appear to be
related to any electronics. Only ten "had the potential for being
interference from electronic devices carried onboard," says
Mr. Sheehan. Of those ten, none involved a cell phone.

In theory, any device that emits electronic waves -- including
laptops, electronic games, pacemakers and hearing aids -- has the
potential to cause interference to an airplane. Part of the problem is
that airplanes are packed with a huge amount of electronic equipment,
from radios and navigational equipment to smoke detectors and
in-flight video. These systems can interfere with one another.
Moreover, planes in the air are constantly flying through what
engineers call a thick electronic soup of emissions from television
and radio towers, satellite transmissions and other emitters.  This
makes pinpointing a single interference event in many cases nearly

Six years ago, Boeing received word that a laptop computer was
suspected of shutting off the autopilot system on one of its jets
during a commercial flight from London to Paris. The pilot conducted
tests by turning the computer on and off, which the airline said again
triggered the autopilot error. The airline "felt 100% confident that
it was a particular laptop" causing the problem, says Bruce Donham, a
senior electromagnetics engineer at Boeing.

Boeing sent engineers to Europe, purchased the laptop from the
passenger, and tried unsuccessfully to re-create the problem from the
same seat and during the exact time of the flight. Later, Boeing
arranged to fly the empty plane on the London to Paris route, moving
the laptop throughout the aircraft. No interference was discovered.
The aircraft maker then brought the laptop back to Seattle and tested
it in a Boeing lab. Mr. Donham says the tests showed no correspondence
between electronic emissions from the laptop and the autopilot

'No Empirical Data'

After its study, RTCA decided to recommend allowing laptops, electronic
games and CD players in the air because it couldn't duplicate
interference.  To be safe, RTCA recommended banning all electronics
during critical phases of a flight, which are generally considered to
be during takeoff and landing, when a plane is below 10,000 feet.

As for cell phones, RTCA's study found "no empirical data" linking
their use to safety issues on the ground or in the air. But the RTCA
ran out of money and time before it could conduct tests using actual
cell phones in various aircraft. So the organization, acting conserva-
tively, recommended that cell phones and other so-called intentional
transmitters -- such as radio-controlled toys -- be banned in the air.

Aircraft makers conducted their own tests for interference as the use
of wireless devices grew. Airbus, the No. 2 plane maker, was close to
releasing its first fully computerized jet in the mid-1980s. It
brought that jet, the A320, to a French Air Force base in Toulon, and
parked it within 10 feet of a series of radar beams and electronic
transmitters, including ones that simulated cell phones and other
wireless devices, says spokesman David Venz.  "There was no impact" on
aircraft systems, says Mr. Venz. Boeing put its jets through a similar
test in 1991, and no interference was found, Boeing says.

But when the airlines, concerned about growing cellular use on the
ground, came to the company seeking guidance in 1993, Boeing advised
them not to allow intentional transmitters, including cell phones, on
the ground or during flight. Mr. Donham, the Boeing engineer, says the
company adopted a "conservative position" because it didn't know
enough to clear them.

Boeing kept testing. In 1995, engineers at the aircraft maker
conducted a four-hour test on a 737, setting up about 20 cell phones
throughout the jet and monitoring the plane's radios, navigational
equipment and other controls. A variety of flight conditions were
simulated. The results: "Absolutely nothing," says Mr. Donham.

Airbus has told airlines it sees no problem with onboard cell-phone
use anywhere. "We haven't come up with any indication" that cell
phones have "any negative impact," says Mr. Venz, the spokesman. Mr.
Donham says Boeing is revising its cell-phone guidelines to suggest
use on the ground is now acceptable. But Boeing still advises the
airlines against cell-phone use in the air because the devices exceed
the company's guidelines for electrical emissions.

Mr. Sheehan, who is also a certified pilot, notes that cell phones are
regularly used on private and corporate planes "thousands of times
every day" without incident. He says he has dialed from the air on
many occasions.  When asked whether cell phones should be included
among the list of devices such as laptop computers that are now
permitted above 10,000 feet, he says "that would be OK. It's not a

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