When I first started flying, airplanes were very basic.
How safe was flying was basically dependant on the skill of the pilots.
Lets face it. Every individual are born differently. Some are born
with the innate talent of handling the aircraft very well whilst others
just do not measure up to scratch. Nevertheless, to be qualified as a
pilot, one must achieve at least an average ability to fly safely. Unlike
driving a car, a pilot cannot afford to make a critical mistake in the air for
to do so would most likely be his last fatal error.
Even skillful pilots make mistakes sometimes. In the past,
aircraft were designed with less safety backups and hence air accidents were often
fatal. One example involved a wide-body airliner in the US which had a
minor problem with landing gears indication inside the cockpit. The crew were trying to determine whether the landing gears were physically
down since one of the lights was faulty. It was at night and all of them
were trying to fix the light without monitoring that the auto pilot wasn't
flying the aircraft as it should be. As the aircraft was quite low, the
slow descent of the airplane was not apparent and it eventually crashed, killing
all on board.
Today, modern aircraft have been installed with
many safety features and the above accident should not have happened at
all if some of the safety systems were inside that aircraft.
Crashing into Terrain?
The aircraft that I am flying, the Boeing 777, is
one of the latest and most modern airplane in the world
today. It has some of the safest features which would
virtually eliminate any uncontrolled flight into terrain. It
is known as the Enhanced Ground Proximity Warning System or EGPWS.
The EGPWS is capable of providing at least 9
warnings to the pilot so that remedial actions can be taken to
prevent any event from developing into something disastrous. This
can save a lot of lives, especially to a pilot who may have the misfortune of
not being particularly alert on that day. Pilots are human
and they can make mistakes but mistakes are costly. The
warnings come in the form of aural and visual messages.
Therefore, when a mistake will eventually end into something
disastrous, the warnings against such an event can certainly save
lives.
Today's modern aircraft fly at a very high
speed. At the cruising speed, the aircraft flies at 9 miles a
minute or about 800 feet a second. During the landing phase, the
speed is much lower at around 170 mph or about 250 feet a second.
Thus, even a few seconds delay in recognizing a potential mistake
can be very costly. With the EGPWS installed, when a tired
pilot (he should not be flying!) is slow in recognizing that
his aircraft is encountering a high descent rate into terrain, he
would be reminded with an aural alert, " Sink Rate!"
from the computer telling him that he should do something to
correct the excessive sink rate. This would have averted an
accident like the one described above.
What happened if the tired pilot did nothing? At
about 50 seconds before crashing, another warning, "Caution,
Terrain!", will come through the overhead speaker
telling the tired pilot to be careful, terrain is ahead! If
no action is taken by about 25 seconds to impact with the terrain
or ground, another final warning "Terrain, Terrain, Pull
Up!" will be issued. The tired pilot must wake up now
and pull up the flight controls to avert the crash into terrain!
Landing Gears, Flaps
and Over-Banking reminder
Amongst the other warnings, the EGPWS also alert the
pilot if he forgets to select the landing gears or flaps when
he is about to make a landing.
Many aircraft have crashed
because the pilot was disorientated in bad weather. A
disorientation arises when a pilot does not know if he was flying
level or inverted. This is mainly due to loss of visual reference
to the horizon. John Kennedy Junior was probably disorientated
before he crashed into the sea.
What is the most likely cause of
the disorientation? Usually it is caused by the pilot over banking
(lifting one of the wings in order to turn) his aircraft. He was not aware he was
turning because of no visual reference to the horizon or he was
too engrossed with other emergencies. An over-banked aircraft will
develop into a spiral dive. If not handled correctly, the
aircraft would crash. The EGPWS has an alert to warn the
pilot when the aircraft is over-banking excessively.
Avoiding Wind-Shear
Many years back, a Boeing 727 crashed before landing in an US
airport due to wind-shear. Could that accident be
averted? Yes, if only the EGPWS was developed then! In the
Boeing 777 today, if wind-shear is encountered on the approach to
land, there would be visual and aural warnings to the
pilot. Firstly, the pilot would be told to look at his radar
display when wind-shear is predicted 3 miles ahead. When the
airplane is 1.5 miles to the predicted wind-shear and if the pilot
did nothing, he would be told by the computer in the form of a
aural warning to take action by aborting the landing and go around!
These are some of the major warnings that are
available in the EGPWS and they do certainly save lives. Today, as more
aircraft are equipped with this system, flying will become
safer. It helps the pilots to detect errors that were not available
in the older aircraft before.
