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- Computer-controlled equipment is vulnerable to electronic
interference
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- Any pilot who flies passenger jets can tell stories of
mobile phones jeopardising passenger flights.
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- Dan Hawkes, head of avionic systems at the Civil Aviation
Authority (CAA), cites a typical incident.
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- "A go-around was initiated by the flight crew -
that is, he aborted the landing, because of interference from a mobile
phone.
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- "He heard the interference in his headphones, and
at the same time his automatic landing system was showing anomalous behaviour.
He decided it was unsafe to continue with the automatic approach."
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- In another incident, the stick-shaker in the cockpit,
a warning signal that the plane is about to stall, started to operate.
The plane was on the ground at the time. A passenger at the back was found
to be using a mobile phone.
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- Anecdotal evidence
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- But most of the evidence is circumstantial and anecdotal.
There is no absolute proof mobile phones are hazardous. But, as Mr Hawkes
explains, even the possibility of interference by mobile phones has serious
consequences.
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- "There's an industry consensus, throughout the world,
that mobile phones are a potential hazard to aircraft and must be switched
off.
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- "A typical aircraft these days could have anything
up to 15 or more radio systems on board. The signals that a mobile phone
gives out could penetrate into equipment, and could affect the operation
of the computer.
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- "The computer may shut down, which would affect
the aircraft's navigation, which in turn would affect the signals sent
to the auto pilot, and the way the aircraft is automatically flown.
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- "The aircraft might go off course, and even might
change height."
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- Carolyn Hawkins, who advises on safety for the pilots'
union, Balpa, says absolute proof is not needed.
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- "If you've got navigational systems being affected,
by whatever it is being affected by, and you turn off the mobile phones,
the laptop, the CD player, whatever, and it corrects it - let's stick with
that, let's be safe in the air."
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- Grave risk
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- Part of the problem is that mobile phones emit signals
even when they are not being used, if users leave them switched on. They
are hunting for their nearest ground station to make a connection.
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- The CAA has decided the chance such signals may interfere
with the complicated electronic systems, now largely relied on by pilots,
is too grave a risk to take.
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- David Learmount, of Flight International, agrees. "As
a result of all this anecdotal evidence which they haven't been able to
prove, they are justifiably nervous. It is a serious matter.
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- "Although it has not been proven that these machines
can make aeroplanes go off course, they really don't want to prove it."
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- It may be that mobile phones are not hazardous to all
aircraft.
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- 'Older models more vulnerable'
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- Neil Whitehouse, found guilty in June of endangering
an aircraft because he refused to switch off his mobile phone, was on board
an older model.
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- Mr Learmount says: "This fellow happened to be using
his mobile phone on board a Boeing 737.
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- "The 737 was designed in the early 1960s, and that
aeroplane has never had its electronic equipment screened against the kind
of emissions that mobile phones put out.
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- "Whereas in the more modern aeroplanes, like the
fly-by-wire, computer controlled Airbus A-320s, A330s, A340s, they have
been screened.
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- "So he could actually say if this aeroplane had
been an Airbus he might well have walked away from the court."
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- But even if you use a mobile phone on an aircraft which
has been screened, it is still against the Wireless and Telegraphy Act.
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- That will be a great relief for people to whom aeroplanes
are about the last place left where you can eat, sleep, think and relax
without being disturbed by electronic warbling.
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