As the search for missingMalaysia airlines flight MH370 continues in the southern Indian Ocean, some key questions remain unanswered.
Here are 10 questions
about what happened to the Boeing 777 that disappeared after leaving KualaLumpur bound for Beijing on 8 March, with 239
people on board.
1.
Why did the plane make a sharp left turn?
Military radar logs
show flight MH370 turned unexpectedly west when it diverted from its planned
flight path, by which time the plane's transponder had already been switched
off, and its last ACARS datalink transmission sent. Sudden turns like this
are "extremely rare", according to Dr Guy Gratton of Brunel
University's Flight Safety Lab. He says the only real reason pilots are likely
to make such a manoeuvre is if there's a serious problem on the plane which
makes them decide to divert to a different destination, to get the aircraft on
the ground. That could be a fire,
other aircraft in the area, or sudden decompression, according to David Barry,
an expert on flight data monitoring at Cranfield
University. Malicious intent - by
a pilot or intruder - is another possibility. But unless the "black box" flight recorders are found, whatever happened in the cockpit at that moment will
remain in the realms of speculation.
2. Is
it reasonable to speculate that a pilot could have intended to kill himself?
There has been much
speculation in the media that suicide might have been behind the loss of the
plane. It wouldn't be the
first time it's happened. The crashes of Egypt Air flight 990 in 1999 and Silk Air flight 185 in 1997 are both thought to have been caused
deliberately by a pilot, though the view has been contested. The Aviation Safety Network says there have been eight plane crashes linked to pilot suicide since 1976. So far, no evidence
has been released from searches of the homes of Captain Zaharie Ahmad Shah and
his co-pilot Fariq Abdul Hamid that back up any similar explanation for MH370.
There has been speculation that Shah may have been upset after breaking up with
his wife, but there is so far no reliable source for his state of mind. It's been
reported police are still examining a flight simulator found in the captain's
home. Barry says the
apparent turning off of certain systems might give weight to the theory, but
"pilot suicide is a theory like any other". Gratton agrees.
"There simply isn't any evidence to prove or disprove it," he says.
3. Is a hijack scenario even possible?
Airliners
have been fitted with strengthened flight deck doors - intended to prevent intruders from
taking control - since 9/11. David Learmount, safety editor at Flight
International magazine, says they are "bulletproof" and
"couldn't be penetrated with an axe".
Sylvia
Wrigley, light aircraft pilot and author of Why Planes Crash, agrees it's
unlikely anyone would be able to force their way in. "Even if the door was
being broken down, they wouldn't be able to get in before there'd been a mayday
call, unless the pilots were incapacitated," she says. However,
one former pilot, who did not wish to be named, has suggested there is
theoretically a way to disable the lock and get into the flight deck. But in
any case, however secure the door, there are times when the door is open - when
a member of the crew either visits the toilet or has to check on something in
the cabin. It's always been pointed out that it would be possible to rush the
cockpit when this is the case. Some airlines, including Israel's El Al, have
double doors to guard against this scenario. Gratton says there's a procedure
which requires a member of the cabin crew to guard the door when it's opened. But
even in the event of hijackers rushing the cockpit, it would be easy for either
crew member to send a distress signal. The
security of the cockpit door offers protection against intruders, but it also prevents action being taken if
something does go wrong. Last month the co-pilot of an Ethiaopian Airlines flight waited for the pilot to go to
the toilet before hijacking the aircraft and flying it to Switzerland. There's
also the possibility that a pilot invited a passenger in. Photographs have
emerged of the co-pilot of MH370 entertaining teenage tourists in an aircraft
cockpit during a previous flight. Boeing said it would
be inappropriate to comment on an ongoing investigation.
4. Is
there an accidental scenario that stands up to scrutiny?
So far most theories
have been based on the assumption that the communications systems and the
plane's transponder were deliberately disabled, a view endorsed by Malaysian
officials. However, Wrigley
believes it's possible a sequence of events may have taken the plane so far off
course by accident. "Something could have gone wrong in stages. A fire
could have taken out part of the plane, or led to some systems failing, but
left the plane intact. Then there could have been decompression - not an
explosive decompression, but a gradual one," she says. Wrigley cites the
Helios Airways flight 522 which crashed into a mountain in Greece in 2005 after
a loss of cabin pressure and lack of oxygen incapacitated the crew, but left
the plane flying on autopilot, as an example. "If the Helios plane hadn't
hit the mountain, it would have kept going until it ran out of fuel. I'm not
saying it's a likely scenario, but it's not impossible," she says. Pilots have pointed
out that one of the very first actions in many emergency drills is to send a
message to air traffic control or some other form of signal. For a purely
accidental scenario to make sense, whatever initial event took place must have
simultaneously knocked out all regular means to communicate with the ground.
5.
Why was no action taken when the plane's transponder signal went off?
MH370's transponder -
which communicates with ground radar - was shut down as the aircraft crossed
from Malaysian air traffic control into Vietnamese airspace over the South
China Sea. If a plane disappeared
in Europe, Barry says someone in air traffic control would have noticed and
raised the alarm pretty quickly. Gratton agrees. "In Europe handover is
extremely slick. "At the very
least I'd expect air traffic controllers to try and contact a nearby aircraft
to try and establish direct contact. Pilots frequently use TCAS [traffic
collision avoidance system], which detects transponders of other aircraft to
ensure they aren't too close to each other," he adds.
Air traffic control
However Steve Buzdygan, a former BA 777 pilot, says that from memory, there's a gap or "dead spot" of about 10 minutes in the VHF transmission before the plane would have crossed into Vietnamese airspace. Learmount says it's also perfectly feasible that nobody on the ground noticed the plane's disappearance. "Malaysian air traffic control had probably handed it over to the Vietnamese and forgotten about it. There could have been a five-minute delay before anyone noticed the plane hadn't arrived - a gap in which nobody pressed the alarm button," he says. Even if air traffic control did notice the plane was amiss, they wouldn't necessarily have made it public, he adds.
6. Why isn't it easier to track missing planes
by military satellite?
The search effort on seas some
2,500km (1,500 miles) to the south-west of the Australian city of Perth has
relied on images provided by commercial satellite companies. Dan
Schnurr, chief technology officer at Geospatial Insight, says there are 20
known satellites that have a resolution capable of obtaining these images in
the "vast tracts of the ocean passing over the poles". Of those,
probably about 10 of them capture images on a daily basis. The
images are beamed down from the satellites in very near real time, and are
probably on the ground within two or three hours of image capture, he says. The
delay in detecting valuable images is down to the time it takes to analyse the
large volume of imagery. There
are also satellite sources owned by the military and government, but these have
not been prominent in the search. This has led to some speculation that the
fate of the plane was known about earlier in the search, but not revealed. Laurence
Gonzales, author of flight 232: A Story of Disaster and Survival, says some
nations are bound to have more sophisticated surveillance systems than they are
letting on. "A very small, fast ballistic missile can be picked up easily,
so how can they lose a big, slow-moving object like a jumbo jet? It tells me
somewhere in the angles of power in the world someone knows where the plane is
but doesn't want to talk about it, probably for reasons of national security
because they don't want to reveal the sophistication of the material they
have... that their satellite technology is so good it can read a label on a
golf ball," he says. But
Gratton says military satellites looking for ballistic missiles probably
wouldn't have thrown up much useful data because they wouldn't have been
calibrated to pick up aircraft of this size. "This aircraft
was seven miles up and travelled at three-quarters of the speed of sound.
Ballistic missiles go up to four or five times the speed of sound, and 30 to 50
miles up - they have very different profiles," he says.
7. Did the plane glide into the sea or plunge
after running out of fuel?
The MH370's final
moments seem to depend on whether the plane was still being flown by a pilot. "If it was under
control, the plane was capable of being glided. The Airbus that went into the
New York's Hudson River lost both engines - which is an identical outcome to
running out of fuel - and the pilot managed to land on the water," Gratton
says. Barry agrees there
could have been a gentle descent. "Aircraft of this size will normally fly
or glide over 50 miles before they hit the sea if they run out of fuel,"
he says. However, if no-one was at the controls, he says the descent could have
been "pretty severe".
8.
Would the passengers have known something was wrong?
If a major malfunction
had not occurred, it is unclear whether passengers would have known anything
was awry, especially if there were no obvious signs of a struggle onboard. Joe
Pappalardo, senior editor at Popular Mechanics magazine, says in most scenarios
where a plane flies off course for hours, passengers can remain oblivious. At
01:00, many would probably have been asleep. In the morning, the astute might
have worked out the Sun was in the wrong position.
Boeing 777s can fly higher than 40,000ft
Malaysian authorities
have said the plane rose to 45,000ft, before falling to 23,000ft, after it
changed course. If that's the case, passengers might have felt the loss of
altitude, according to Pappalardo. However one theory is
that the plane's apparent climb could have been designed to induce hypoxia -
oxygen deprivation - which could have knocked people unconscious and even
killed them. Wrigley thinks it
could have played out in one of two ways. "In the horror story version
passengers would have realized something was wrong as the plane climbed - and a decompression event would have led to oxygen masks coming down, and an
awareness that oxygen was limited. A better scenario is they didn't know
anything had happened until impact," she says.
9.
Why didn't passengers use their mobile phones?
One commonly asked questions is why, if it had been obvious something was
wrong, passengers wouldn't have used mobile phones to call relatives and raise
the alarm. This seems especially puzzling in light of the example of United
flight 93, where passengers communicated with people on the ground after the
plane was hijacked during 9/11.
It's been stated that
it's extremely unlikely that anyone could get mobile signal on an airliner at
30,000ft. Barry agrees the chances of a mobile phone working on the plane were
"virtually impossible". "It can be hard to get a signal on a
remote road, let alone seven miles up, away from mobile phone masts, travelling
at 500mph," he says.
Arguably the most baffling
thing to a layperson about the disappearance of MH370 is how it is even
possible for a plane of this size to disappear so easily. In an era when people
are used to being able to track a stolen smartphone, it's perplexing that
switching off a couple of systems can apparently allow an airliner to vanish. Barry
says the technology exists to allow planes to give off full real-time data. The
problem is planes are "snapshots in time from when they are
designed". "We're
doing research into devices that will allow aircraft to start transmitting
information by satellite when something unusual like a fire or decompression
happens, but it's hard to fit things into a plane retrospectively. "The
777 went into service in the early 90s... the technology is of that era,"
he says. However,
Gratton says ACARS would have done the job if it hadn't been turned off. A more
complex satellite system would also be open to that risk, he argues, unless the
industry wanted to go with = a system that couldn't be manually switched off,
and that would come with other risks.
"It's not a particularly easy question. Is the bigger risk an aircraft going missing, or electronics overheating? Both situations can't be met," he says.
"It's not a particularly easy question. Is the bigger risk an aircraft going missing, or electronics overheating? Both situations can't be met," he says.
Copyright of Vanessa Barford (BBC News Magazine)