Stn Cdr Odiham's Remarks
Whilst I am quite used to Cazatou ignoring what the AAIB really concluded about the possibility of a technical malfunction, and the proper legal definition of gross negligence, I have to wonder what Chinook240 is trying to achieve by resurrecting old and discredited arguments, and by trying to down play the Stn Cdr Odiham's experience (presumably at least as far as the Mk2 was concerned his experience was significantly greater than either of the two officers who reached the gross negligence verdict - and although I do not know I assume he was anyway a very experienced RW pilot). Can I yet again remind you of what the Stn Cdr Odiham actually said before his conclusions and recomendations became "disconnected" from his earlier comments - I have always wondered why! Incidentally the Stn Cdr Odiham does not use the word negligence at any time in his remarks - to support the earlier post from Brian Dixon.
The Board then opine, in making this profile dovetail with other evidence, that the crew, faced with the expected deteriorating weather, consciously elected to make a climb on track over high ground and in doing so used a speed and power combination that is unrecognisable as a Chinook technique. I find this difficult to believe; such actions would go against all the crew’s instincts and training. Moreover it is the very antithesis of the professionalism and careful planning that had gone before. Even taking into account the factors which the Board feel could have deceived the crew into believing a high speed cruise climb would have given them sufficient clearance over the Mull I, and the few, senior Chinook operators that I felt able to consult, find this suggestion incredible. I will take the 3 key factors cited by the Board in turn:
a. Precision of GPS The Board's view is that the crew could have placed inordinate reliance on GPS accuracy. It true that during visual navigation aircrew place great reliance on the GPS - it is rarely more than 200 metres in error. However, training and normal practice throughout the helicopter force is such that no crew would trust a GPS position close to a potentially dangerous obstruction unless at the very least, they had the opportunity to cross check with another aid. Furthermore, the Board suggests that GPS errors led the crew to underestimate the nearness of the land and caused them, in turn, to underestimate the ROC required. Although I accept the board's argument about the geometry of the tangential approach to land and the disproportionate effect on the closeness to land a small cross track GPS error would cause, I do not believe that any crew that close to a obstruction would be concerned about niceties of a few hundred metres. I find the concept that an undue reliance on the GPS would make the crew accept a cruise climb is stretching credibility too far.
b. Aircraft -Speed. Although not stated as such, the implication in the Board's findings is that the transit speed approaching the Mull of Kintyre was unusually high. I doubt this. An assessment based on a time/distance calculation, shows that the average groundspeed from take off to impact was, depending on the parameters used, in the range 135-155 kts which, when corrected for the forecast wind, gives an IAS of between 115-135 kts. In practice, I believe the crew adopted a cruise IAS of 135 kts, which is both range speed and is commonly accepted as the maximum speed for passenger comforts. However, the Board suggest that as the Mk I Chinook experienced high vibration levels above 135 kts, which are not so pronounced in the Mk II, the crew were seduced into accepting a higher speed than that and, as they were unfamiliar with flying at such speeds, this caused them to miscalculate the gradient of the climb that would be achieved. Again I believe this stretches credibility too far. I do not believe even the most junior crew would have selected a cruise climb technique that close to the Mull whatever the cruise speed. They would only have entertained such a profile by starting the climb well clear of the high ground and probably as they coasted out from Northern Ireland. The Board tacitly acknowledges this in para 44, where they accept that the crew’s general NVG training, enhanced by the specialist SF Flight training package, is such that "it (is) most likely that the crew would have adopted (the technique of a cyclic flare and max power climb) in the event of inadvertently entering cloud whilst aware they were directly approaching, and close to, high ground.
c. Distraction. The Board does not discount distraction during the decision making process. While I fully accept, and indeed agree strongly, that distraction may have been a factor in this accident, I do not accept the implication that the decision making process was a complex one and was thus particularly vulnerable to distraction. The decision to be made was relatively simple and the courses of action available when approaching high ground in poor weather would have been ingrained in this crew, and indeed all helicopter crews, since basic training. Those alternatives are to: slow down and if necessary stop; turn away from high ground and if necessary turn back and, if a climb is required, do so on a safe heading at full power at the maximum rate of climb speed to at least Safety Altitude (SA). Moreover, it is pertinent to note that as members of the SF Flight, this crew were given additional training in the techniques of making landfall from offshore both by day and by night and they practiced it regularly.
An Alternative View
2. In looking for alternative causes I have no new evidence to call upon, and all I can do is put a different emphasis on factors already considered by the Board. By working “forward” from the departure point, I conclude it is highly probable that rather than electing to climb over the Mull the crew saw the coast and decided to continue VFR to the west of the Mull Peninsular. The evidence of the yachtsman who saw the aircraft about 2 -3 nm SW of the Mull gives a good idea of the weather and the aircraft’s height and attitude just before the crash. At about 17-30, only 30 minutes before the crash, the yachtsman then about ¾ mile from the Mull reported that the lighthouse and the cloud covering the land behind the lighthouse were clearly visible. Just before the accident the same man, now 2 to 3 miles from the Mull, reported that the aircraft was straight and level at a height of between 2-400 ft well below cloud level. He assessed cloud cover as 80% and the visibility as about 1nm, limited by haze. He also reported the cloud as structured which, in aircrew terminology may mean layered. After the aircraft passed the yachtsman any deductions about what happened become more speculative but I believe that given the reported weather, the crew saw the Mull and it was this sighting that prompted the Waypoint (WP) change at 1.75 km.
3. This WP change is crucial in trying to understand what the crew intended to do. if they had intended to abort at this stage and climb over the Mull despite the difficulty, which would have been so obvious to them, of clearing the high ground they would not have selected the Corran WP. Firstly, it removed from them the only easily interpretable information about the location of the high ground. Secondly, it was of little practical value; the crew would not have been able to climb to SA on track to Corran, in the hope of reverting to low level VFR, because of the forecast level of the 4ºC isotherm. If they intended to climb over the Mull then only sensible option would have been to keep the lighthouse WP on until well clear of it and then to select the chosen diversion airfield. On the other hand, selection of the Corran WP was entirely appropriate if the intention was to follow the western coast of the Mull Peninsular and regain the planned track at the first convenient opportunity. In arriving at this alternative scenario I am now faced with the same problem that faced the Board - how did the aircraft get to around 500 ft, at 150 kts IAS with a ROC of approx 1000ft per minute, which are the computed starting parameters of the final 18 seconds of flight?
4. Whilst tackling this issue the Board were unable to totally discount the following factors:
a. Spatial disorientation or visual illusion.
b. An unregistered technical malfunction.
c. Human factors.
Any of these, or a combination of them, could, in my view, have sufficiently distracted the crew from the task of turning away from the Mull to cause them both to inadvertently enter cloud and then to fail to take the correct procedure for an emergency climb in a timely manner. The Board consider engine control system malfunctions and it is particularly relevant to note that at this stage of the Chinook Mk II's service spurious ENG FAIL captions, lasting on average 7-8 seconds, were an increasingly frequent occurrence. These are now well understood but at the time they were not. Had such an indication occurred it would have caused crew considerable concern particularly as they were over the water with no obvious area for an emergency landing. Such a warning would also have required an urgent and very careful check of engine instruments and FRCs.
Can I suggest, as has been done before, that unless you KNOW what happened you all stop misquoting facts to support your personal opinions - opinions which you are, of course, entitled to hold, but which have no relevance to what the Mull Group have been working for 13 years to achieve and which is on the bottom of every one of Brian Dixon's posts - justice!
JB