A day after it disappeared en route from east Java in Indonesia to
Singapore, mystery surrounds the fate of AirAsia flight QZ8501 and the
162 people on board.
No debris from the Airbus A320-200 has so far been recovered, and
Indonesia's National Search and Rescue Agency chief Bambang Soelistyo
said Monday "the hypothesis is the plane is at the bottom of the sea".
Following are some questions surrounding the disappearance and search,
and answers by industry experts.
Q: What impact could bad weather have played on the plane's fate?
Air traffic controllers lost contact with the twin-engine aircraft
around an hour after it left Juanda International airport at Surabaya
in East Java at 5:35 am Sunday (2235 GMT Saturday).
Shortly before disappearing, AirAsia said the plane had asked
permission from Jakarta air traffic control to deviate from its flight
plan and climb above bad weather in an area noted for severe
thunderstorms.
Gerry Soejatman, a consultant with the Jakarta-based Whitesky Aviation
chartered flight provider, said the verdict is still out on whether
bad weather conditions was the "primary factor or just a contributory
factor" for the disappearance.
"Based on the public information we have, the pilots turned to the
left of its designated route, and also requested to climb to a higher
altitude," Soejatman told AFP.
"Approval was given for the left turn but there are indications the
plane climbed without approval. If that is the case, the turbulence
could have been severe and the pilots made a decision to save the
aircraft rather than wait for approval," he added.
Anthony Brickhouse, a member of the International Society of Air
Safety Investigators, said it "is not atypical to have a
pre-programmed flight path and then something happens and the pilots
try to adjust it".
"Airliners in general tend to avoid thunderstorms as much as possible
to give passengers a smoother ride," Brickhouse, an assistant
professor at Embry-Riddle Aeronautical University, told AFP.
"Right now, the fact that they were trying to avoid bad weather
doesn't tell us a lot in the grand scheme of things."
Q. Have there been other plane mysteries like this?
Malaysia Airlines Flight MH370 disappeared while flying from Kuala
Lumpur to Beijing on March 8 with 239 passengers and crew.
The Boeing 777-200 aircraft is believed to have crashed in the Indian
Ocean far off Australia's west coast after diverting off course for an
unknown reason and flying for several more hours over the remote
waters.
An intense air and sea search failed to find any wreckage from the
aircraft, while an underwater search has been underway for weeks with
no result.
Air France Flight 447 crashed into the Atlantic Ocean in June 2009
while on a flight from Rio de Janeiro to Paris, killing 216 passengers
and 12 crew. Debris was not found for days and it took years to locate
the wreckage. Investigators eventually concluded that both technical
and human error were to blame.
Adam Air Flight 574 with 102 people on board disappeared from radar in
January 2007, also at its cruise phase during a domestic flight in
Indonesia. Debris was found nine days later after an extensive search
and it took months to recover the plane's black box.
Indonesian authorities said the pilots lost control after becoming
preoccupied with malfunctioning navigational equipment.
Was Flight QZ8501 flying too slowly when it disappeared?
Some experts have said initial readings of radar data have shown the
plane was flying much slower than it should have been when it
disappeared.
In the Air France Flight AF447 crash in 2009, it is believed a
build-up of ice on "pitot tube" instruments caused the pilots to
receive distorted data on airspeed before the aircraft went down.
"Although any attempt to explain the reason for the disappearance of
the AirAsia flight is pure speculation at this time, we can't but
notice at least one apparent similarity with another famous crash: Air
France 447," wrote aviation blogger David Cenciotti on
theaviationist.com
He added that low ground speed could have been caused by strong headwinds.
Soejatman said early readings from a leaked air traffic control image
circulating online showed Flight QZ8501 was "extremely slow".
"If the plane happened to be going below stall speed, then well, you
will fall out of the sky," he said.
Can we rule out terrorism or a hijack attempt?
Experts say it is too early to rule out any possibility.
"As an investigator, I am trained to keep all possibilities on the
table until evidence suggest otherwise," said Brickhouse.
"Right now, I have not seen anything that could be associated with any
kind of criminal act."
