I thought very little was made of the error in the manufacturers manual regarding the length of time between engine flameouts. Stated as 4 mins, yet even with the supply tank contents as prescribed in ideal conditions, it was nearer 1 min 30, MAX. Manual has now been corrected, but if I had been over a city centre and that close to base, I know how I would have been thinking of using those 4 minutes ... And it doesn't involve an emergency landing in the city centre.
You've nailed it. Sadly this incident was completely avoidable. The sequence of events can be divided into two parts. The events leading up until the moment that the first engine to fail started sucking air, and the events thereafter. We will never know for sure what led the pilot to turn and leave those transfer pumps off in the first stage but bad design that failed to foresee this scenario, ensured that what was a drama became a crisis when the second engine started sucking air just 30 seconds later, exacerbated by the pilot's belief from training that he had 4 minutes breathing space if he had recognised by that point what was going on.
A very good pilot simply ran out of time. 30 seconds is too short a time for the second engine to fail for the same fuel starvation reasons.
The report states:
"Corrective action is being taken by the manufacturer to amend the potential
engine flameout interval to a more accurate figure in the next revision of the
SDS manual, scheduled for publication in December 2015." The manual says that the 4.5kg difference between tanks allows 3-4 minutes between engine flame outs.
It is my belief that give the pilot 3-4 minutes rather than an unexpectedly short 30 seconds and he would have had a very good chance of getting that craft and its occupants down intact.
It is not the manual that needs updating, it is the design that needs changing to increase the differential in tank size, ensuring that the pilot gets his full four minutes. Maybe it is not in the AAIB remit to make this recommendation but it seems an obvious fix and provides a safety net to the same situation developing again.