What happened to AirAsia Flight QZ 8501: Your questions answered

As the headline in CNN-Hongkong, The sudden disappearance of AirAsia Flight QZ8501 in Indonesian airspace has fueled a host of questions: What caused the loss of contact? Why Asia again? Is air travel still safe?

CNN asked readers and viewers to tweet questions, using the hashtag #8501qs. We were inundated.

Here are answers to some of the more commonly asked queries.

1. What happened exactly?

Some basic facts are known about Flight 8501's journey before it

lost contact with air traffic control.


The Airbus A320-200 took off from the Indonesian city of Surabaya at 5:36 a.m. local time Sunday with 155 passengers and 7 crew members on board. Its destination was Singapore, a journey that usually takes a little over two hours.

At 6:12 a.m., one of the pilots asked air traffic control permission to turn and climb to a higher altitude to try avoid bad weather, according to Indonesian officials.

Minutes later, the plane disappeared from air traffic control's radar.

At 7:55 a.m., Flight 8501 was officially declared missing. Its last known position was over the Java Sea, between the islands of Belitung and Borneo.

The majority of those on board the plane are Indonesian. There are also people from South Korea, Britain, France, Malaysia and Singapore.

But beyond those points lies a huge amount of uncertainty.

2. If the pilots requested a higher altitude because of weather, why didn't air traffic control provide an alternative path?

Air traffic control approved the pilot's request to turn left but denied permission for the plane to climb to 38,000 feet from 32,000 feet, Djoko Murjatmodjo, an aviation official at the Indonesian Transport Ministry, told the national newspaper Kompas.

The increased altitude request was denied because there was another plane flying at that height, he said.

Djoko suggested that Flight 8501 ascended despite air traffic control denying it permission.

3. Could it have been a terrorist act?

With uncertainty over what exactly happened to the plane, theories about what happened are proliferating. But officials haven't so far suggested there was any foul play aboard Flight 8501. A clearer picture is likely to emerge once the plane is found.

One expert offered CNN a less sinister theory about what might have happened: The plane stalled mid-flight.

A screen grab purportedly leaked by an Indonesian air traffic controller appears to show that Flight 8501 was rising in altitude but was losing speed at a velocity that was too slow to sustain flight, said Geoffrey Thomas, managing director at the aviation industry site airlineratings.com.

The data taken from the screen grab comes from an Indonesian pilot who was given the screen grab anonymously by an air traffic controller who had been tracking the flight, according to Thomas.

Thomas added that the typical procedure for a pilot is to push the nose of the plane down to gain airspeed and exit the stall, but in very rare circumstances atmospheric conditions can make that impossible, leading to a situation that is not recoverable.

4. Could the plane have landed safely on water, like the U.S. Airways plane did on the Hudson River?

Experts say it's possible but unlikely that Flight 8501's pilots pulled off a feat similar to that of Chesley Sullenberger in 2009.

The Airbus A320 is equipped with a ditching switch "that essentially turns the plane's fuselage into a boat," Alan Diehl, a former Air Force and NTSB accident investigator.

"If they got the aircraft down on the water safely," he said, "it should be floating."

But underwater search expert Christine Dennison said she didn't think a landing on water was very likely. She said she remained hopeful that there might be some survivors, though.

"We may have a rescue effort under way that will prove very fruitful. There are just so many variables," she said.

Indonesia's top search and rescue official, Bambang Sulistyo, said Monday that the "early conjecture" of authorities is that the plane is at "the bottom of the sea."

5. How is this similar to the disappearance of Flight MH370?

Superficially, yes, there are similarities with Malaysia Airlines Flight 370, which disappeared in March: A passenger jet flying over Southeast Asian waters in the early hours of the morning drops off radar, prompting a huge international search.

But analysts say there are several noteworthy differences.

In MH370's case, the pilots made no radio transmissions about the plane's mysterious change of course, deepening the puzzle about what happened. But one of the Flight 8501 pilots told air traffic control what he wanted to do -- turn and climb to avoid bad weather.

The AirAsia flight is believed by Indonesian officials to have gone down into the Java Sea, a much shallower and busier body of water than the southern Indian Ocean, where MH370 is thought to have ended up.

Finding Flight 8501 will almost certainly be much easier than the still ongoing hunt for MH370, said Steven Wallace, former director of the Federal Aviation Administration's Office of Accident Investigations.

It's "very unlikely that we're going to see anything remotely close to what we saw with Malaysia 370," he said.

6. Is it something about Asia that makes air travel unsafe?

It's been a year of several high profile and deadly air disasters -- three of them linked to Malaysia. But experts says the skies are still safe.

This year has had the lowest number of crashes since the late 1920s, according to Geneva-based Bureau of Aircraft Accidents Archives.

This year's number of crashes at 111 is down from 139 last year, says the bureau, which defines an air accidents as "any event where aircraft suffered such damage that it is not in a position to be used anymore and that it is removed from service."

But there is bad news too. If everyone aboard Air Asia is dead, the number of fatalities in 2014 will reach with 1320, the most since 2005, when 1,463 people died.

Asia has had a particularly bad year. Experts admit it's strange that Flight 8501 should have dropped off radar in the same region of the world as MH370.

"It's eerie, it's unusual or just kind of spooky that this would happen in this area, but we don't know the facts yet," said Peter Goelz, former managing director of the U.S. National Transportation Safety Board.

7. If a similar weather pattern existed within United States, would an airline go ahead with the flight ?

"The aviation nations of the world, ours included, allow the airlines to make good decisions," said CNN aviation analyst Mary Schiavo. "Air traffic control does not shut down the flight lanes, they don't shut down the traffic corridors."

"Most major carriers have their own in-house meteorological departments, and they help the pilots make those decisions," said Schiavo, a former inspector general for the U.S. Department of Transportation. "In the U.S., often they do it prophylactically. If there's a bad storm or a hurricane or whatever coming, they simply cancel the flights to avoid the massive mess that will ensue if they have to reposition the planes. But it's up to the airline."

Les Abend, a former Boeing 777 captain, says that "airline pilots always attempt complete avoidance, steering a wide berth around thunderstorms."

"Unfortunately, route restrictions, other aircraft traffic and altitude constraints sometimes prevent our flights from deviating as far as we'd like," he wrote in a commentary for CNN. "This isn't to say we jeopardize safety, only that we might not be able to provide the most comfortable conditions for flying."

8. If radar was tracking the plane, why don't we know where it went below altitude?

"At this point we may know, but that information hasn't been transcribed yet," Abend said.

Sulistyo, head of Indonesia's national search and rescue agency, said Monday that the theory that the plane is now at the bottom of the sea is based on the plane's flight track and last known coordinates.

Now that a day has passed since the plane went missing, investigators should have more data to help them find it, said Peter Goelz, former managing director of the U.S. National Transportation Safety Board.

"They've had a full 24 hours now to gather all of the available radar data from all of the available sources," he said. "They should be able to put that together, along with any satellite data, and have a more precise location on where to target their search."

9. Why can't inflight cockpit recorders be recorded in real time?

Something along those lines has long been in the works, but it's not a reality yet.

"It's a matter of cost," says Abend. "We do have some aspect of streaming data in the form of ADS-B, which is Automatic Dependent Surveillance-Broadcast information, which uses satellite."

But not all airlines fully subscribe to the service.

The disappearance of MH370 has spurred calls for international action to improve in-flight tracking.

In a preliminary report on MH370, Malaysian aviation authorities recommended that the International Civil Aviation Organization look into the benefits of introducing a standard for real-time tracking of commercial aircraft.

But in the past, skeptics have cited several reasons why in-flight data uplinks might not work, including high costs, limited bandwidth, security concerns, privacy issues and cumbersome aviation bureaucracies.

10. How many airline disappearances remain a mystery?
Such situations are very rare. But the puzzling disappearance of a jetliner without a trace has happened several times in aviation history.

Some still remain unsolved decades later.

Among the most notable are a Boeing 727 that vanished after taking off from Luanda, the capital of Angola. Its whereabouts are unknown to this day.

There is also the case of EgyptAir Flight 990, which crashed into the Atlantic off the Massachusetts coast in 1999. Speculation remains about the cause of the crash, which killed all 217 people aboard.

And despite an official investigation, conspiracy theories still abound about the midair explosion of TWA Flight 800 shortly after takeoff from New York City in 1996.

11. Was the crew inexperienced?

Not according to AirAsia.

Flight 8501's captain has a total of 20,537 flying hours, with 6,100 of them with AirAsia Indonesia on the Airbus A320, the airline said. That's a respectable amount of flying time.

The first officer has a total of 2,275 flying hours, AirAsia said. That's also a reasonable amount for the position.

12. What lessons from the failed MH370 search are being applied to this latest search?

The main lessons seem to be in terms of communication.

Malaysian officials came under criticism for confusing and contradictory statements during the immediate aftermath of the disappearance of MH370.

Family members of passengers and crew complained about their treatment.

This time around, government and airline officials appear to treading more carefully.

AirAsia CEO Tony Fernandes tweeted that the company's priority is "looking after all the next of kin" of crew and passengers.

And the search appears to be getting off to a more efficient start. Indonesian officials quickly posted a search plan, indicating ships from its navy -- as well as assets from Malaysia, Singapore and Australian -- were being called to help.
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