Hot 'n' High
You stated that the "original valid findings of the BOI were overturned by two AVM's."
The BOI was convened by AOC 1 Gp (an AVM). This Inquiry was number 13 in the list of ongoing BOI's (plus a few Unit Inquiries). The President of the BOI was appointed by the AOC to conduct the Inquiry on his behalf.
This BOI felt unable to agree on a cause for the accident but suggested that "the crew had selected an inappropriate rate of climb to clear the Mull". The AOC was convinced that the appropriate action that the crew should have taken was to climb at maximum rate until at or above Safety Altitude whilst turning away from the high ground that they knew lay ahead. Such a course of action when facing IMC at low level is drummed into all aircrew throughout their training. Failure to do so, as suggested by the BOI,
amounted to Gross negligence.
This viewpoint was shared by the AOC STC (an ACM) as the Reviewing Officer, and by the CAS (another ACM) who also reviewed the proceedings before publication.
The AAIB Inspector stated that there was "no evidence of any technical malfunction which could have caused the crash." Famously he went on to add "that doesn't mean there wasn't one". True, but so is the corollary - it doesn't mean there was one either.
Because there was no evidence of any technical malfunction there was no fleetwide programme of rectification or modification in order to prevent a further occurence because no technical fault had been identified as the cause of the crash.
It is now more than 13 1/2 years since this tragedy - years that have seen the commitments placed on the Chinook fleet increase markedly. They are operating under conditions that have not been seen by the RAF since WW2; with limited resources and under constant threat of hostile action. This length of time is greater than the combined durations of the Boer War, WW1 and WW2 - yet there has been no repetition of this tragedy.