Some thoughts about the scale of any recovery operation
I think it's worth putting some sort of perspective into the logical next step of the operation: that of locating the wreck and the FDR & CVR.
We don't have to go further back in time than a dark eastern Canadian night in early September 1998...
SWR111 impacted intact at 20° AND, ~110° right bank at 350kts: a ‘steep water entry’. At impact Eng 1 was producing ‘high power’, No 2 was windmilling following shutdown in flt and No 3 producing slightly more than flt idle.
Although it impacted at speed, the acft was not in freefall thus terminal velocity had not been achieved and the acft did not break up prior to hitting the water.
All souls perished instantly from the deceleration (350g) and only fragments of human remains were recovered, to be identified by dental records and/or DNA.
A seismic event was recorded by a land station. The wreck came to rest a few miles offshore at a depth of 55m. The resultant ‘relatively compact’ debris field measured 125 x 95m. The terrain was undulating, silted and at bottom around 1m visibility. The accident occurred on 2nd Sep 98, with the FDR recovery on 6th Sep and the CVR on 11th Sep. From 'only' 55m. The FDR/CVR situation was compounded by their respective ULB broadcasting on the same frequency, frustrating efforts to pinpoint their origin, and in a state of becoming detached from either recorder. Jet-A fuel was apparent on the surface for a few hours prior to evaporating.
Transpose this scenario with the aid of the few known factors thus far in the AFR447 case, and it is fairly obvious that if we, for the sake of simplicity, take the depth of the Atlantic in the general region of the point of impact as 5500m (10 times the depth of SWR111 and hundreds of miles from land), then the debris field would be of the order of 13 x 10 kilometres.
This, in mountainous terrain, with the valleys mainly filled with pooling mud.
And that’s assuming that the acft impacted in one piece.
If it had reached terminal velocity (rough calcs according to Stoke’s Law would put the plunge at around 400~500kts depending on superstructure presentation relative to the surface) and consequently broken up on its way down, just multiply the debris field projections by the number of impact points, and compare that with the scale and effort that went into the SWR11 recovery and you’ll quickly appreciate why the French are already hedging their bets and warning that the FDR & CVR may well never be found.
The apparent lack of any appropriable seismographic event may conceivably be due to a large number of fragments impacting at different velocities, at different locations and slightly different times.
This, however, runs diametrically contrary to the hitherto lack of flotsam and jetsam on the surface. More break-up prior to impact would presumably imply more lighter debris, spread over a significant area.
In summary the rule of thumb in this contributor’s humble opinion would be that the ‘needle-in-the-haystack’ operation – on paper – would command the effort of the recovery of SWR111 raised to the power of ten. At a conservative estimate.
How far do you go? How far would you need to?
Sincerely,
PB (one who lost two colleagues in the pointy end of SWR111)