Thanks for that Caz and Walt,
However, from the House of Lords Inquiry
After obtaining weather reports Flight Lieutenant Tapper decided that the flight to Fort George would be a low-level sortie flying under visual flight rules (VFR) and intimated that he was not intending to fly under instrument flight rules (IFR). Indeed flying under IFR in the vicinity of the mountains to the east of Ballachulish and Fort William would not have been permitted by the icing restrictions.
and then referenced to
Instrument flight must be conducted at or above a height ("safety altitude") 1000 ft above each of the high obstacles on the intended route (Q 280). Flt Lt Tapper had calculated the safety altitudes for the latter part of the sortie as 5900 ft Mull-Corran and 5800 ft Corran-Inverness. The CA Release precluded flight in an indicated temperature below +4° C. A weather aftercast shows that this temperature would have been reached at 5000 ft; and the Sheriff calculated that the crew may well have expected to reach it much lower, at 2500 ft (determination p 120 of HL Paper 25)
so its not as simple as it sounds, is it!? In my view, because of the CA RTS, the crew would have been pre-disposed to remaining VMC below. A large piece of Gruyere....but not containing much cheese!
Certainly, the BOI report may have influenced the Reviewing Officers but since 1994/5, this fact (and more about the FADEC/DECU) have surfaced than the BOI had time to consider - which renders the BOI report and the subsequent verdict incomplete, illogical and unsafe - admittedly with hindsight.
flipster
ps Perhaps the Rad Alt settings that Walter mentions are worthy of consideration. Would anyone who operated Chinnys care to comment?
BTW Walter, Tuc is right to point out the underlying failiure of the airworthiness system as a major contributory issue. By that I mean that if the crew had indeed been flying an aircraft
that did not have the icing limitation, then maybe they might have have 'punched out' of low-level prior to the turning point (or LZ if you like). However, as BD points out we don't know what the crew could see from the cockpit, nor what was said, discussed or actioned.....almost everything else is guesswork and does not form the legal basis for 'with no doubt whatsoever'.