With the search already into its 18th day, marine recovery teams are pressed for time to detect and recover the data recorder, which may have sunk to the bottom of the southern Indian Ocean, potentially dragging the secrets of the flight’s final moments with it.
Crews know they have to work fast, according to Jim Gibson, general manager of the deep-ocean survey firm Phoenix International, which is assisting the U.S. Navy mission to locate the Boeing 777.
That’s because acoustic beacons, or locator "pings" from the black box will probably fall silent within two weeks, Gibson told CBC News.
"At some point, the pinger will simply run out of power, and that’s usually in about 30 days," he said. "Once you figure out when the aircraft went into the water, you go 30 days from that point, and that’s its shelf life."
Phoenix International’s “Batwing-like” towed pinger locator (TPL) weighs about 31 kilograms and can detect a black box’s signal ping from about a mile (1.6 kilometres) away, Gibson said.
His firm assisted in the Atlantic Ocean recovery effort of the doomed Air France Flight 447 that went down five years ago on its way to Paris from Rio de Janeiro, killing 228 people. Phoenix International is now the contractor operating the U.S. Navy’s deep ocean search and recovery equipment for the Malaysia Airlines jet.
A Phoenix International equipment team is en route to Australia to scour an area about 1,970 kilometres southwest of Perth — a region at about 40 degrees south latitude that oceanographers call the "Roaring Forties" due to it having some of the most treacherous seas on the planet.
That remote region is where a British satellite analysis tracked the aircraft’s last known position before it vanished on the morning of March 8, local time, with 227 passengers and 12 crew members on board.
"The weather down there is very challenging — high winds, high seas, fronts that come through rather quickly. It makes working in the deep ocean very, very difficult," Gibson said.
Wind speeds in the area often reach 40 knots (74 km/h) and huge swells early Tuesday forced Australian Maritime Safety officials to suspend the air and sea search.
The depth of the water could be more than 4,000 metres in some parts around that area – four times deeper than the Gulf of Thailand in the South China Sea, where radar had tracked the airliner earlier this month.
Phoenix International’s equipment is rated to descend to a depth of 6,000 metres.
Relatively flat terrain
"But it’s a remote location. Just the logistics of getting out there, that’s a challenge," Gibson said, noting it would take an aircraft roughly four hours to arrive.
"If you need to get another widget, well, you’d better not have left anything back at station."
Scripps Institution of Oceanography professor Ken Melville reviewed the underwater terrain around the survey site and said the deep interior is "relatively flat" compared to areas further north, although it’s difficult to generalize.
"There are ridges further north, and trenches further north, but that doesn’t seem to be the case here," Melville said from San Diego.
Flatter terrain could make it easier for deep-sea vehicles to navigate the seafloor to find a black box, the recovery of which could help clear up one of the biggest aviation mysteries in history.
Toronto-based aviation expert Jock Williams said the machine functions as two devices — a black box known as a cockpit voice recorder and another, more potentially revealing device called a flight data recorder.
Williams said the cockpit voice recorder logs all the sound from the cockpit, including intercom chatter, conversations from the flight deck, and radio transmissions.
"If you had a party whistle and you blew it, it would record that, too," he said.
The drawback, he said, is that the apparatus only keeps recent audio because it constantly re-records over old information.
Williams said the real potential trove of information for aircraft accident investigators would be the filght data recorder, which logs more than 100 “data spots” such as airspeed, outside air temperature, altitude, engine power and oil pressure for both engines.
"It will show you if the pilot initiated a left turn with the yoke. If he initiated it by turning the auto-pilot control head, it will tell you that." he said.
"It will tell you whether anything was said on the plane’s six independent radios. It just won’t tell you what was said.”
'Virtual playback room'
Aside from the TPL for detecting pings, Gibson said Phoenix International can deploy autonomous submersibles and sonar vessels, then use a remotely operated underwater vehicle to verify whether a piece of debris dropped to the seafloor.
Although marine trawlers will be working against the clock, all isn’t necessarily lost if the battery powering the pinger on the black box completely drains.
"In the case of Air France 447, they never did hear the pinger, but we were still able to locate and recover the black box," Gibson said. That mission was made easier, however, because floating debris had been spotted.
As for whether the black box will be intact, Williams said they almost always are, even following crashes.
If a black box is recovered, Williams said it will likely be hooked up to a "virtual playbook room" used by investigators to recreate the flight deck environment, complete with multiple screens and a replica instrument panel. The cockpit voice recorder would be playing at the same time.
"You watch and see from an above view, the side view, the back and front — what the plane is doing, complete with the mountains and hills you would be seeing. It’s uncanny," he said.
"They get that black box and the mystery is gone. We may not ever know why this happened, but I’ll tell you this, we’ll know what happened accurate to within milliseconds."