There could be six possible reasons for the disappearance of aircraft
In MH370’s case, what happened to the distress transponders or beacons?
MALAYSIA Airlines Flight MH370 took off from Kuala Lumpur in the early hours of March 8, headed towards Beijing. Within two hours of takeoff, the aircraft lost contact with all air traffic controllers.
There was no distress call made by the pilot or flight crew. The aircraft was flying at 35,000 feet and the weather was clear. No trace of the aircraft has been found until today.
What is the best explanation for this?
At this point, all this is only speculation as there is not enough information. However, historical evidence suggests that there could be six possible reasons for the disappearance of aircraft.
1) A combination of technical and pilot errors leading to a snowballing effect
There is no single factor which generally leads to an airplane crash but a combination of technical glitches and pilot decisions. Each of these glitches and decisions taken independently are harmless and often happens
It is the combination of these factors that leads to a catastrophe. This is what happened to Air France 447. There was no distress signal from Air France 447 as the pilots did not realise that they were going to crash until 10 seconds before crashing.
2) Structural disintegration
This can refer to the structural failure of the aircraft which cause the pilots to lose control of the aircraft. This last happened in 2002 to China Airlines Flight 611, during its cruise at 35,000 feet.
Flight 611 was a Boeing 747 aircraft and the reason for that crash was faulty repair. The Boeing 747 is an aircraft with older technology (20 years earlier) compared with a Boeing 777. The Boeing 747 entered service in 1975 while the Boeing 777 entered service in 1995.
The new aircraft coming into the market use better materials, technology and maintenance schedules compared with earlier aircraft.
3) Human factors
Deliberate actions by the passengers or pilots that may cause the aircraft to crash. The Sept 11, 2001 attacks on the World Trade Centre in New York brought this to the fore.
4) Bad weather
Inclement weather conditions such as snow, fog, rain and ice can affect the performance of the aircraft, which is likely to result in a crash. These weather conditions affect the critical stages of aircraft like landing and takeoff.
However, MH370 had clear weather throughout the flight, and disappeared during the calmest period of flight, the cruise.
5) Total electrical failure
This predominantly occurs in general aviation aircraft. There are three types of electrical power sources – two generators (each engine has one), an APU (Auxiliary Power Unit) and RAT (Ram Air Turbine).
For the aircraft to have total electrical failure, all three systems should have failed at the same time.
This is quite rare. This happened to a Qantas flight in 2008 in Bangkok. The Qantas flight landed safely with backup power from APU. Electrical failure from generators is an incident that needs to be reported back to the air traffic controller for a request for rerouting.
It is also possible that the aircraft was hijacked to an unknown location. However, this possibility can be ruled out based on the following reasons:
Skipping all the radars – when there are many country borders around the vicinity of the aircraft’s last point of contact, the aircraft is a big aircraft (the radar cross-section of Boeing 777 would be bigger);
Being able to hide the aircraft and passengers for five days;
Using a runway/ airport with no witnesses; and
No group claiming to have hijacked the plane.
What kind of distress signal is expected when a crash happens? Will electrical failure affect the distress transponders or beacons?
Regulations require commercial civil aircraft to have Emergency Locator Transmitters (ELTs). They are activated during a crash based on the G (gravity) force they experience or by pilots’ input.
Another beacon is attached to the flight recorder or the black box which is called Underwater Locator Beacon (ULB). The black box beacon is activated when it comes in contact with water.
Assuming the aircraft crashed on water, the ELTs would have sent signals, but they are not waterproof. The ULB starts emitting signals the moment it touches water.
Important facts to note:
Although the aircraft might be emitting an automatic distress signal, there might not be anyone listening to it every minute. And these signals have a range within which there might not be anybody listening to it.
A crash sometimes happens within a time-frame of 15 minutes (AF447) and pilots may realise that a crash is imminent only five to 10 seconds before a crash. Only after 30 minutes to an hour, does the air traffic controller realise that something is wrong and starts looking for the aircraft, by which time, the beacons are well underwater.
The ULB can emit a signal for hundreds of miles. But if the black box is covered with debris or falls into a trench at the bottom of the sea, then the strength and range of the signal would be lower.
The ELT and beacons use their own batteries and electrical failure does not affect them.
Should the beacons run out of battery, what are the options?
The batteries of the beacons of the black box beacon are designed to last 28 days. If the black box beacon battery dies and the plane is not located within that time, then the only hope is to find the debris and try to work backwards from there on.
Ravi Madavaram is a consultant with the Aerospace & Defence Practice at Frost & Sullivan Asia Pacific
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