Three days after the Malaysia Airlines plane went missing, the authorities were still trying to figure out what could have happened to the plane with 239 people on board.
Finding the Boeing 777's flight-data and cockpit-voice recorders - collectively known as the black box - would help investigators unravel what happened in the final moments of MH370.
Black boxes, which in fact are usually painted bright orange, are usually installed in the tail of the plane which is subject to the least impact in the event of a crash. The exact location a black box is installed depends on the individual plane. Possible spots include the ceiling of the galley, in the aft cargo hold or in the tail cone that covers the rear of the aircraft.
They are designed to withstand 3,400 times the force of gravity on impact, making it highly likely the boxes will have withstood any breakup of the plane, said Bloomberg News.
But retrieving the black box in the event of a crash could take a long time. Investigators need to be nearby to pick up the pinging noises emitted by emergency beacons from the black box.
The recorders would normally begin sending signals once they are submerged, with the pinging lasting for 30 days until independent power supplies run out. Search teams can use underwater microphones to help find the black box. According to Bloomberg News, units made by Honeywell emit signals that can be heard from 2.8 miles deep.
When Air France Flight 447 with 228 people onboard went missing in 2009 while it was flying over a large body of deep water, search-and-rescue operations found debris and some of the bodies in the weeks following the crash. But it took almost two years to find the main wreckage and the black boxes, deep in the middle of the Atlantic Ocean.
The Malaysia Airlines incident is likely to rekindle a debate about whether black box flight recorders should be replaced with satellite-based systems capable of sending back telemetry in real time.
Such systems exist. According to The Wall Street Journal, a few hundred airplanes around the world have already been outfitted to stream live data via satellite.
But not many carriers have equipped their aircraft with this because of the rarity of in-flight disasters, and the high cost involved in upgrading equipment and putting in more satellite connections. Sending all the data from each flight in real time via satellite would be extremely costly. According to Bloomberg Businessweek, a 2002 study by L-3 Aviation Recorders and a satellite provider found that a United States airline flying a global network would need to spend US$300 million (S$380 million) per year to transmit all its flight data, even assuming a 50 per cent reduction in future satellite transmission costs.