The AAIB do not, of course, and quite rightly, apportion blame. Their job it to investigate EVERY aspect of any incident, including examining the "due diligence" of every party involved which in any way could have contributed to this incident. In order for the AAIB to do their job properly, and to the benefit of everybody, they cannot be compelled to give evidence of their findings in court. We discussed this earlier.
There is, of course, much to be learnt from the comprehensive details contained within the report, however, the AAIB do summarise their findings in the Conclusions.
I make no comment at this stage but I feel the the extract from the Operation Aspects section of the Conclusions "probably" explains why the maneuver was not executed successfully. I would point out that further sections of the Conclusions go on to consider the factors that resulted in such a terrible loss of life.
Extract from CONCLUSIONS
17. The minimum height loss during the downward half of a looping manoeuvre
in the Hawker Hunter is between 2,600 and 2,950 feet (including 100 ft
for instrument reading error), when flown at the values of aircraft mass
and density altitude relevant to the accident.
18. The pilot stated that he required a minimum height of 3,500 ft at the apex
of the manoeuvre to ensure that he completed it 500 ft or more above the
ground (as required by his display authorisation).
19. The aircraft achieved an apex height of approximately 2,700 ft.
20. The airspeed at the apex of the accident manoeuvre was 105±2 KIAS,
which was at the lower end of the pilot’s declared airspeed range of
100 to 150 KIAS.
21. The aircraft was lower than required at the apex because it entered the
manoeuvre below the target airspeed, because less than maximum
thrust was applied during its upward half, and because any rolling
element initiated before the aircraft reached the upward vertical would
have further reduced apex height.
22. The entry height of the manoeuvre was consistent with the 200ft minimum
height on the pilot’s DA for a Jet Provost; the apex height and speeds
on the accident manoeuvre were consistent with those flown in the Jet
Provost the previous weekend.
23. The pilot stated that he would abandon a ‘bent loop’ manoeuvre if the
minimum entry speed, or the minimum gate height at the apex, were
not achieved. He did not abandon the accident manoeuvre when these
minimums were not achieved.
24. It is possible that the pilot misread or misinterpreted speed and height
indications during the manoeuvre, or recalled those for a different aircraft
25. The pilot had not previously rolled the Hawker Hunter at the low airspeed
encountered at the apex, and was not sure that a roll could be achieved
at that speed.
I had just got round to seeing the glass as half full instead of half empty, when some sod came and drank it......