The debate unearthed the picture-postcard image above, the route operated by BA 'til a helicopter like this crashed in poor visibility into the sea in continuous descent, killing nineteen passengers along with the cabin attendant.
The accident report published two years later runs to thirty-four pages and like so many, includes granular detail whilst at the same time being able to avoid elephants in the room. On balance however you have to consider it worthy and best that could be done in the circs... pilots and investigators have a trammelled view of flying that sometimes means they miss either the obvious or the extenuating.
For instance BA mandated a requirement for 900m visibility during the approach to the island, during which the crew figured they had settled at around 250 feet and 90 knots, or a hundred miles an hour. In conditions of calm sea and haze, or low-lying mist prone to form above a calm sea... in the absence of a visible horizon and any texture on the water's surface, how does anyone possibly estimate visibility given it is generally done with reference to fixed points on land?
Visibility as against RVR or runway visual range, which is instrumented, has always been left to pilot judgement and had been optimistically estimated since the days of the Wright Brothers, leading to innumerable collisions with the ground, or sea.
In this case it would be fair to say the captain would be flying on instruments for a knowledge of any horizon whatsoever, whilst winging the visibility in a way we'd all done at one time or another. For example too, any ship was supposed to be avoided by 500 feet whether vertically or laterally, and this would surely have been done on the basis "There's not normally anyone there..." as much as anything, as we are all aware of how much ground for instance a car covers at 100 m.p.h. each second and even if that is whilst looking out the window (which here was only an intermittent activity on the half of both crew).
The report essentially says that the captain was using the instruments primarily to judge the power and pitch adjustments required of reducing forward speed, whilst the co-pilot was glued to the Decca Navigation system and/or weather radar so as to confirm the final navigation toward St Mary's airfield. This would involve each of them looking out front either intermittently or not at all, and overlooking continued descent toward the surface.
Here's the thing though that the report does not really emphasise: in circumstances like these, the appearance of sea and sky blends into what is called in photographic studios (and I've used them often) an 'infinity wall' where the estimation of horizon, range, speed and even which way up you are becomes impossible absent the use of instruments that provide such information.
In Alaska, in such weather and for landings on or around snow, pilots would drop three bin-bags out the door prior to an approach to provide a visual reference as to all these vital criteria: three elements being the key to triangulation and much else.
It was on a trip to Innsbruck organised for the entire company by Titan Airways that I found myself up a mountain on a ski-run in an accumulating fog that forced me to a halt. And here's the thing ~ standing upright I still had no notion of whether I was slowly sliding forwards, or backwards or sideways in the absence of any reference at all, the snow having merged seamlessly with the weather.
We've only limited means of a sense of self in such conditions, one being the weight felt on whichever part of the body; another acceleration (though not velocity) by the inner ear; and crucially what we can discern from our purview that gives us cues as to how we are oriented, in which direction we are headed and at what speed.
In truth, all of this was likely missing in that helicopter in 'similar but different' circs, and most of the people on board ~ yet ironically, not the pilots in the line of fire ~ would have born the brunt of what in fairness were meteorological conditions of the sort that were ill-defined by the airline at the time.
Which in fairness, was more used to airliners than helicopters: the hierarchy at the time would have been drawn from the RAF, to which I had a brief exposure myself. The best-performing during training were streamed onto fast jets, the median lot on to transports and the 'could do betters' on to helicopters.
This despite, from what I saw of it in a Bell 205 simulator, it being in many ways the more difficult to master.
The author passed both pilot and navigator aptitude at the RAF's selection centre at Biggin Hill, but failed overall in view of the fact his A-level results were shit and he'd an ambiguous attitude toward killing people... even from a distance.
