What
are the dangers of a thunderstorm to a plane?
Thunderstorms can have very strong winds called updrafts and downdrafts
that cause what is called turbulence. Turbulence makes it very difficult
to control the airplane. Wind from a thunderstorm near the ground
can also be very dangerous to planes. These winds can change speed
and direction quickly. These winds are called wind shears. During
bad storms there may be hail stones. These can break the plane's
windshields and damage the plane and its engines. Heavy rain can
sometimes get into the engine and cause it to fail. Lightning at
the height the plane is flying can be very bright and it might even
temporarily blind the flight crew.
Can
Lightning strike a plane?
Lightning does hit airplanes and when it does it can damage the
electronic equipment needed to fly the plane. Lightning research
done during the 1980s by NASA had an F-106B jet fly into1,400 thunderstorms
and lightning hit it over 700 times. The lightning did not damage
the airplane but scientists found out that it could damage electronic
systems on the plane. This led to requirements that all aircraft
electrical and electronic systems have built-in lightning protection.
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What
has been done to keep planes safe from lightning?
At any given time there are more than 2,000
thunderstorm throughout the world, producing 100 flashes of lightning
per second. Planes can not totally avoid lightning and thunderstorms
but due to learning more about severe thunderstorms and how they
might affect the safety of those in flight, scientists and engineers
have helped developed ways to make flights safer.
Many planes have their outer areas (called skins) made from aluminum.
This is a metal that is a very good conductor of electricity. If
lightning strikes the plane, most of the lightning current remains
on the exterior of the aircraft and flows along the exterior and
then away from the plane. Newer airliners are being made of composites
which do not conduct electricity as well, but the outer skin is
embedded with a layer of conductive fibers designed to carry the
lightning currents.
Systems
have been designed to help protect all of the computers and instruments
that control everything in the airplane. Lightning protection engineers
make sure that damaging surges can not reach the equipment inside
the aircraft. Shielding, grounding and surge suppressions devices
are used to help protect cables, circuits, and equipment. Every piece
of equipment that is essential to a safe flight and landing of an
aircraft must be tested and certified that it is protected against
lightning. The Federal Aviation Administration (FAA) sets the standards
and put the regulations in place.
In
addition, we now have more sophisticated instruments to help detect
lightning and predict weather conditions. Doppler radar is weather
radar that measures the direction and speed of a moving object,
such as drops of precipitation. This can help those in the airport's
flight control centers know where the storms are located. Lightning
detection networks have also been developed which can track lightning
strikes all over the country using the National Lightning Detection
Network. This network uses magnetic sensors and computers to detect
when and where lightning strikes. If a supercell (the most dangerous
type of thunderstorm) is spotted, pilots and airport personnel are
alerted
Even
though the passengers and crew may see a lightning flash and hear
a noise if lightning strikes their plane, nothing serious should
happen because of the lightning protection built into the aircraft.
Pilots sometimes report a temporary flickering of cabin lights or
some brief interference with their instruments.
Smaller
planes are probably struck less frequently by lightning because
of their small size and because they often avoid weather that might
include severe thunderstorms and lightning. Larger airliners may
delay flights to protect passengers and flight crew as well as ground
crews that are handling baggage or preparing planes for departure.
Once in the air, pilots often fly detours or change altitude to
avoid severe storms and the turbulence or lightning.