alphafloor, you ought to include the Brazilian government as a co-conspirator. If the Brazilians had searched the area west of the track, instead of concentrating on the area east of the track, the debris field might have been discovered by June 2nd, and more proximate to the actual crash location.
ratherbeflying, the signature that the fuselage may present to sonar may be a lot smaller than you apparently expect. If the fuselage is still largely intact and on a slope, the profile presented might be more the cross-section of an 18 foot hollow tube, rather than a nice horizontal presentation of 150 feet or so of metal.