French investigators are warning that they may be forced to conduct their inquiry into the loss of the Air France Airbus A330 without crucial evidence, given the ocean depth and sub-sea terrain.
Bureau d'Enquetes et d'Analyses director Paul-Louis Arslanian, speaking during a briefing in Paris, said that the recovery effort faced regions of extremely deep water and terrain which was "more of mountains than of plains".
He says the inquiry "cannot be satisfied with 80% understanding", but admits that it may have to proceed with the prospect of a full conclusion never becoming known.
Arslanian says that, without the cockpit-voice and flight-data recorders, he would be "pessimistic about reaching established facts". But even if they are retrieved, he says, the BEA "cannot guarantee" that it would be able to go further that it could without them.
He adds, however, that the inquiry team is "not ill-equipped" and that it will "try to do the best it can" under the testing circumstances.