AIRLINE pilots risk destroying their aircraft through heavy-handed use of the
plane’s rudder, a safety watchdog is warning. Poor training means most pilots
are unaware of the danger—which could affect the action they take during a
hijacking.
The warning comes from the US National Transportation Safety Board (NTSB),
which is midway through its investigation into the fatal crash last November of
an Airbus A300 which smashed into houses in the Queens district of New York
shortly after take-off. Investigators believe the plane broke up after flying
through turbulence from a jumbo jet that took off ahead of it. The Airbus lost
its tail fin and rudder in mid-air, causing the aircraft to disintegrate.
As one part of its ongoing investigation, the NTSB has been trying to find
out what could cause a tail fin and its rudder—a large, hinged slat
forming the rear of the tail fin—to shear off. This has never happened in
any previous air accident.
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The Airbus’s flight recorder shows that its rudder performed several large
side-to-side swings, after the plane encountered the second of two bouts of
turbulence. Although the NTSB doesn’t yet know if the rudder movements caused
the tail fin’s failure—or even if the pilots caused the rudder
movement—investigators are looking into the theory that the pilots may
have used the rudder pedals too vigorously to cope with the turbulence.
Worryingly, the NTSB has discovered that many pilots don’t realise that
excessive use of the rudder can damage a plane. They appear to believe that a
device called a rudder limiter, which stops a full swing of the rudder to one
side at high speed, also protects the plane against full side-to-side rudder
swings. But it does not do that.
Nor do aircraft makers test the effect of extreme flip-flopping movements of
the rudder when a plane is certified safe to fly. Yet pilots are not taught this
in training, says NTSB chairman Marion Blakey. “Certain rudder inputs by pilots
could cause a catastrophic failure of an airliner’s vertical tail fin,” she
says. In addition, the NTSB says pilots need to be made aware that at high
speeds, full rudder deflections can be achieved with smaller, lighter rudder
pedal movements.
The NTSB’s findings apply to all makes of commercial airplane. It has called
on the US Federal Aviation Administration, which regulates the airlines, to
order pilot retraining on rudder safety issues. FAA spokesman Les Dorr says the
organisation is likely to respond quickly.
The French Accident Investigation Bureau (BEA) agrees with the NTSB and is
making similar recommendations, while Britain’s Civil Aviation Authority is
“looking closely” at the issue. Carolyn Evans, technical secretary of the
British Airline Pilots Association, says that while pilots are trained to
understand the load forces on aircraft, “the profile of this particular area of
training may need to be raised”.
The NTSB’s new advice may also affect what pilots do to prevent hijackers
taking over their plane. Since 11 September, they have been advised to use
extreme aircraft manoeuvres to knock hijackers off their feet. But if heavy
rudder use risks damaging the aircraft, they’ll have to think again. The FAA
says pilots shouldn’t attempt any extreme manoeuvre that isn’t in a plane’s
flight manual.