It is rare for a jetliner to crash without being found for lengthy periods, or ever. But it isn’t unprecedented.
No wreckage of a lost Military Air Transport Service charter flight, operated in 1962 by Flying Tiger Line has ever been recovered. The Lockheed L-1049 Super Constellation, carrying 107 passengers, disappeared during a flight from Guam to the Philippines and was presumed to have crashed.
According to the Aviation Safety Network, the search covered 144,000 square miles using 48 aircraft and eight surface vessels.
The long hunt for the wreck of an Air France jetliner that slammed into the Atlantic Ocean in 2009 also illustrates the challenges of underwater recoveries. Some parts were found within a couple of days. But to recover more, there were three explorations of the suspected crash zone, each with progressively more sophisticated equipment.
After the first two searches proved fruitless, some Air France officials argued for giving up. But officials at the plane’s manufacturer Airbus—notably current Chief Executive Tom Enders —persisted, hoping to find the plane’s data recorders and clear any lingering questions. The third search, costing millions of dollars, found wreckage of the Airbus A330 in April 2011.
The search effort was bolstered by data gathered by the French air-crash investigation agency, which one year after the crash dropped buoys near the plane’s last known position to measure currents. Analysis by specialists at the University of Massachusetts indicated that searches had been focused too far from the likely crash site.
One of the first big underwater searches of the modern jet occurred in 1987, after the crash of a South African Airways Boeing 747 jumbo jet off Mauritius. The plane crashed in deep water en route to Johannesburg from Taipei, but the rough location was known because the crew had been in radio contact with controllers due to an onboard fire.
Within weeks, much of the wreckage was discovered almost 15,000 feet down. Special undersea vehicles took hundreds of hours of video and examined much of the wreckage. Ultimately, only about two dozen objects were recovered, including the cockpit voice recorder. But investigators were able to establish a plausible scenario of an onboard fire that began in the plane’s cargo area.