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MISSING MAS FLIGHT: Answers to key questions on MH370 disappearance
Publication Date : 13-03-2014
Why did the plane or pilot not send out any distress signal?
In a crisis, the drill for pilots is to fly, navigate, communicate - in that order.
The cockpit crew of Malaysia Airlines Flight MH370, which went missing en route from Kuala Lumpur to Beijing, did not send out a distress signal. This suggests that they faced a catastrophic problem, said observers.
Nearly 100 per cent of the time, pilots are able to regain control of the aircraft and call for help, said Captain Mok Hin Choon, president of the Air Line Pilots Association-Singapore. He did not comment on the incident but spoke in general terms.
He said: "Even if there is total engine failure at 35,000 feet and you're not able to restart the engines, the plane can continue to glide and you have about 15 to 20 minutes minimum to do what you have to, send out the distress signals and make an emergency landing."
Captain Manmohan Singh, a pilot turned flight instructor, said: "Depending on the severity of the situation, it is possible - though rare - that pilots don't even get past the first stage of flying.
"When you're not even able to control the aircraft, that's when planes fall from the sky."
Presumably, this was what happened to MH370, other experts said.
Even if pilots do not call for help, today's planes are capable of sending out their own distress signals. But not all airlines have the systems to monitor these.
Michael Daniel, a retired United States Federal Aviation Administration official who has investigated several air accidents, said it is compulsory for airlines to have communication systems to reach cockpit crew if needed.
But it is not mandatory for them to monitor real-time flight data. Most global carriers would have such systems, but it is not known if MAS had this.
Why can't the ringing cellphones of MH370 passengers be used to track the plane's location?
Nearly 20 families managed to get a ringtone on the phones of the passengers days after the plane disappeared, according to reports. But experts said hearing a ringtone does not mean the call has gone through.
"Callers may hear a ringback tone as programmed by the network operator while the network is trying to connect to the phone - whether the phone is online or not," said Clement Teo, Singapore telco analyst for US-based market research firm Forrester.
The ringing may last a few seconds depending on whether it is recognised as a local or overseas call. "It does not mean that the phone is ringing on the other side," he said.
Even if the cellphone is ringing, it may not mean that it is ringing on the aircraft. The ringing could be due to the common practice of travellers forwarding calls to another number before boarding their plane.
Several telecom network experts who declined to be named said cellphones work only if they are not under water and are near a cell tower, which typically covers a radius of 500m to 1km.
While smartphones are known for their poor battery life - typically up to 24 hours - they can run for several days after a full charge if they are set to flight mode.
For tracking by cell tower to be possible, the phone must be powered to transmit signals to the cellular network. Another way to track cellphones is via the Global Positioning System (GPS).
"GPS tracking is possible on certain smartphones even when they are set to flight mode," said security expert Aloysius Cheang, Asia-Pacific managing director of global computing security association Cloud Security Alliance.
There are so many satellites in space. Why have none of them captured the location or movement of MH370?
China has deployed 10 satellites in the search for MH370, while commercial satellite firm DigitalGlobe has roped in 25,000 volunteers online to look at its high-resolution pictures.
But experts say that while satellites can deliver high-resolution pictures and make out items as small as 1sqm, using them to find a lost plane may be challenging.
Even so, can the historical data of satellites show the direction the plane took after it lost contact with air traffic controllers?
This would be hard as it was flying at night, said Dr Santo Salinas, a senior research scientist at the National University of Singapore's Centre for Remote Imaging, Sensing and Processing.
What about using satellites to look for the aircraft or debris from a crash?
This is possible, said experts, but only if it is known roughly where to look.
In the tropics, cloud cover can also obscure a satellite's field of vision.
Where a plane goes down is another issue. It is harder to find something on land, said Dr Salinas, as cities, forests, houses with metallic roofs and so on will show up with different brightness. The ocean, on the other hand, is mostly uniform, which makes it easier to spot objects that stand out.
Even after satellites have taken pictures, the images still need to be scanned by human eyes. "It's like looking for a needle in a haystack," said Dr Salinas.