Ask Captain Lim

According to Arnold Barnet, the chances of you being involved in a fatal air crash can vary between whether you are on an international or domestic flight and whether the airlines you are boarding is from a developed country or otherwise.

Air travel today is generally very safe. Some may then ask, “Ah, why do I hear a lot about air crashes?” Sure, every air crash is promptly reported worldwide. But do you know that more people die in car crashes in 6 months than have died in all plane accidents in the last 100 years?

They do not believe that crossing a road, climbing the ladder or having a soak in their bathtubs are more risky than taking a journey by air in a major airline. Yes, flying was not very safe in the beginning when air travel was at its infancy. Today, modern technology has made the airplane very reliable.

Flying in the early years

When I first started flying, airplane instruments were very basic. How safe was flying was dependant on the skill of the pilots. As the saying goes, to err is human. But one cannot afford to make a serious error where flying is concerned because lives are affected. Hence, human error is the last link to making flying safer. Fortunately, aircraft manufacturers have built in many safety and warning systems to compensate for the possible human errors.

Every individual is born differently. Some are born with the innate talent of handling the aircraft very well whilst others are not so. Hence, to be qualified as a pilot, one must demonstrate at least an ability to fly safely. Unlike driving a car, a pilot cannot afford to make a critical mistake for to do so would likely be his last error. (The 2005 Helios Boeing 737 in Cyprus and the recent 2007 Sao Paulo TAM Airbus A320 crashes are just two good examples)

In the past, aircraft were designed with less safety backups and 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 was 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 deeply engrossed with trying to fix a light bulb without monitoring that the autopilot was not flying the aircraft. It was in fact descending. 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 if some of the safety warning systems were in that aircraft.

Crashing into Terrain

The Boeing 777 is one of the latest and most modern airplanes in the world today. It has some of the safest features, which would virtually eliminate any uncontrolled flight into terrain. This system involved is known as the EGPWS (Enhanced Ground Proximity Warning System).

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. The warnings come in the form of aural as well as visual indications. Therefore, when a mistake will eventually develop into something dangerous, the warnings against such an event can certainly save the day.

Modern aircraft today fly at a very high speed. At the cruising level, the aircraft flies at about 9 miles a minute (550 mph) or around 800 feet a second. During the landing phase, the speed is 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 fatigued 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 informing him that he should do something to correct the excessive sink rate.

What happened if the tired pilot did nothing? At about 50 seconds before crashing, another warning "Caution, Terrain!” would come through the overhead speaker warning the pilot to take action as terrain is ahead. If no action is taken by about 25 seconds to impact, another final warning "Terrain, Terrain, Pull Up!" would come on. The tired pilot must wake up now and pull up the flight controls to avoid crashing into the terrain!

Landing Gears, Flaps and Over-Banking reminders

Besides 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. 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, especially if the pilot accidentally flew into clouds when he was not trained to fly under such conditions. John Kennedy Junior was probably disorientated before he crashed into the sea. The 2004 crash of the Boeing 737 from Flash Airlines, an Egyptian Air Charter company may be another example.

What is the most likely cause of disorientation? In most cases, the pilot was over banking (lifting one of the wings in order to turn) his aircraft without realizing it. He was not aware he was turning because of no visual reference to the horizon or he was too engrossed with other tasks. 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 have been averted? Yes, if only the EGPWS was developed then. On the Boeing 777 today, if wind shear were encountered on the approach to land, there would be visual and aural warnings. Firstly, the pilot would be notified 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 took no action to avoid it, he would be alerted by an aural warning to abort 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 to aircraft in the past.