Chinook - Still Hitting Back 3 (Merged)

[walter kennedy]

BOAC
As has happened so often on this thread recent readers ask questions that have been covered before; in the past I have labouriously restated the case with supporting data where available to save them the effort of “trawling” through so many posts which, largely due to so much going around in circles on legal niceties and other innocuous aspects, is indeed a tedious business – in doing so I have been accused of writing “voluminous” posts, etc.. However, with respect to your having asked pertinent questions and having made statements strongly in a way as to focus debate, I will try and clarify my view again.
I have never assumed that they were in VMC at the position where they changed the waypoint in the SuperTANS, a position that, despite the usual attempts by regular contributors to argue against anything being able to be determined about this crash, can be regarded as accurate enough (Boeing analysis, AAIB) to be used an important reference point and as it was so close in, an important factor in trying to determine their intentions.
My assumption about the conditions they would most likely have been exposed to at that point is based upon my personal experience of years of sea trials off the NW coast of Scotland in all weathers/seasons: according to what witnesses have said of that day and the prevailing wind and humidity that day (so typical) I believe that the conditions would have been so very common for a late afternoon at that time of year – orographic cloud at about 800 feet, uplope mist from 2-300 ft running up the slope but of limited thickness and patchy (a phenomenon known as “speed up” occurs as the air mass hits a headland and the layer near the surface is compressed, speeds up, drops in temperature and reaches its dew point before the bulk of the air mass – you can see it on a micro scale regularly and predictably in the afternoon at Gib when a Levante pushes up the water catchment concrete slopes). I have posted links to photos of such mist, including on the Mull, on this thread page 138 on 14 Oct 2007 posts #2756, 2757, 2758, & 2759.
On several occassions, I have travelled in a Wessex with the big door open slowly along the shoreline with steeply rising adjacent ground – to the seaward, clear – 100 yards onshore, mist forming up the slope such that while it was easy to follow the shore, it would not have been easy to approach it quickly and judge the turn along it – you could see the ground (the layer of mist being thin and irregular) but it would have mage range judgement from a distance a real bitch. Add to this that the orographic cloud covered the larger topographic features (hill tops, etc) reducing the general sense of orientation/spatial awareness.
Coupled with years of precise close-in coastal navigation locating wreckage for diving – and, on land, a lot of orienteering in the hills in all weathers/seasons – all requiring accurate position fixing as opposed to just avoiding/bypassing hazards – and, in pre-GPS days, reliant heavily upon reference to the topography, it is my opinion that in anything but the clearest visiblity casual judgment of range (without recognising a familiar feature, say a building or sheep) is dangerously unreliable – to an extent that persons not having had to make accurate determinations cannot appreciate.
If you refresh yourselves as to their track relative to the shoreline as they approached on 027 (say, from the annotated charts I posted) it is possible that they may have not had consistent visual contact with the light house although it was visible from out at sea further away from the coast.
So I am saying that they were almost certainly in clear air at the position of waypoint change and could make out the shoreline but range judgment would have been hard – yet at that position they turned right 8 degrees and reduced power (Boeing analysis showed reduced air speed on final leg and power found at matched intermediate level); on this latter aspect, it is hard to reconcile this change of power (and a measured one at that to have achieved match/balance) with any kind of jam – uncontrolled run up would not have resulted in a reduced matched situation as this and to have reduced power in a controlled way from that as used in the cruise so far does not make any sense in the presence of other problems in proximity to the hazard – the only sense in this is if they were planning on landing or closely approaching that LZ (which other settings suggest). That reduction in power severely limited the responsiveness to emergency manouevres – by way of examples, a sharp turn or sudden cyclic climb could not be achieved until the FADEC and turbine lag had passed and the engines could spool up sufficiently otherwise the manouevre could be accompanied by an immediate loss of height (the power levels for slowing down in level flight only being enough to support the weight of the machine while level, there being no thrust vector pushing along that could be instantly redirected to increase lift). If you are letting speed wash off in an approach to landing you are in a minimal power regime for emergency action – a worst case, the Chinook with lots of power already being used in manouevres/maintaining high speed is a very agile beast.


I do not believe that they would have put themselves in that situation, so close in and with reduced power as to so limit their options in case of emergency, unless they had thought themselves a bit further away from the landmass. As experienced pilots in such areas and conditions they would surely have realised the danger of visually misjudging distances and of course the SuperTANS had told them that they were already very close in before they ditched waypoint A – but this captain in particular would not have trusted the SuperTANS to have kept them safely away from the hazard, its potential error after a sea crossing being greater than the distance left to the shoreline and so should have turned away earlier than the position of waypoint change if just routing by the Mull was their intention. You do not have to be in VMC to rely upon a navaid to keep you clear of it when the murk is in a fixed location – ie on the landmass – visually, it would have been as hard to judge distance off that landmass that day as it would be to judge one's distance off a cloud or fog bank, but at least they knew geographically where it was and that it was fixed as they could have seen the shoreline during the approach from some distance off – as I have tried to explain above, typical in that area, and surely they would have recognised it as such.


I put it to you all that if a system was being demonstrated that allowed a pinpoint approach, but for whatever reason the ground equipment was further up the slope than it was supposed to be, then they have expected to have slowed down enough to acquire the LZ visually or decide on a wave off as they reached the shoreline but in the event were too close, too fast – further, they had turned before they were in line with the LZ such that they were heading for higher, more steeply rising ground not as benign as would have been the case for a wave-off if their path had been over the LZ at 035. The CPLS system gives accurate range and approximate bearing – had such a system been demonstrated, all that is known about this crash is explained by the ground equipment being ½ mile or so up the slope, they would have thought they needed to turn right towards it and had ½ mile more to go than they had.
It would be nice if those experienced with the use of such equipment could educate us all on its use on operations (eg extraction, resupply, marking of isolated hazards near FAFs, etc).
Also, as it was fitted to HC2 Chinooks by early '95, it would be nice to know when it was first trialled in the UK, how it was fitted, how the data was displayed, etc – why is it such a big secret, a taboo subject? Sensitive because of ongoing operational use or because of this crash?
And if such a demo was the case, would an exercise call sign like F4J40 have been appropriate?

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