Few clues to the destruction of Air France flight AF447 are evident from initial photographs of the wreckage, but discovery of the crash site brings resolution closer than at any point in the frustrating 672-day search.
While the precise location has not been disclosed, the wreck lies on a mid-Atlantic abyssal plain just north of the last confirmed position - 2.98°N, 30.59°W - transmitted by the Airbus A330-200 before it disappeared en route to Paris on 1 June 2009.
AF447's debris emerged about nine days after the specialised vessel Alucia arrived, on 25 March, to begin comprehensively mapping the ocean floor, at depths exceeding 3,500m (11,500ft) - the fourth dedicated mobilisation of resources aimed at finding the missing aircraft.
But initial data suggests the three previous searches only narrowly missed the crash site. The latest search focused on systematically scanning every unchecked region, beginning with a full sweep inside a 37km (20nm) circle centred on the A330's last known position.
France's BEA investigation agency has identified structures including the wing, main landing-gear, and the General Electric CF6 engines.
There is no immediate indication that the search has located the rear fuselage. The flight recorders, crucial to filling a gaping void in understanding of the accident sequence, are installed behind the rear pressure bulkhead.
Airbus and Air France co-funded the latest search and confirmation of the recorders' location will result in a fifth phase being launched to recover them.
"We simply cannot stay in the unknown," says a senior Airbus source close to the search effort. He says the search team will perform a "flyover" of the wreck to map the debris field, which is about 600 x 200m.
"This discovery, coming only days after the fourth sea search was launched, is good news indeed since it gives hope that information on the causes of the accident, so far unresolved, will be found," says Air France chief Pierre-Henri Gourgeon.
The Airbus source indicates that a review of data from the earliest search is likely to be carried out to examine whether there is any evidence that flight recorder beacon signals were unknowingly detected.
Failure to locate the beacons forced the BEA to explore a search area of 17,000km² (6,560 miles²), a situation exacerbated by lack of sufficient ocean current data and limited access to sophisticated underwater equipment. "It has been a big challenge," it says, but describes the discovery as "fantastic".
PICTURES: Images from the Air France A330 crash site at the bottom of the ocean floor