A lot of risk factors have been identified:
· Insufficiently clear APBSS approach guidance chart
· Assumption that existence of APBSS in FMS database meant it was safe at 200ft
· Lack of total clarity of Blackrock height on 1:500,000 VFR chart
· Blackrock in some databases not others, at varying heights
· Blackrock not in EGPWS database
· Probably poor radar operating technique so Blackrock, a 300ft high 700ft wide island, was not seen
· Too slow reaction by crew to FLIR operator warning of Blackrock
· And no doubt several others
BUT.... the existence of all these risk factors would not have mattered at all if the aircraft had been at a sensible height, not 200ft.
To me the main cause of this accident was the crew’s decision to descend to 200ft for a 12 mile transit (including approach to Blackrock) to Blacksod. It should be obvious that the chance of hitting something in poor vis/IMC increases the lower you go, the longer you do it. 10 miles at 200ft is going to carry 10 times the risk of hitting something as 1 mile at 200ft – which should have been all that was necessary for this approach. They could have even used the APBSS route guidance, which at sensible heights would have fine, with a let-down to 200ft to say BKSDB.
The world is too big and changing too fast for any nav databases to be 100% reliable everywhere. Just look at the rash of emerging wind turbines across northern Europe! Approval and verification processes understandably take time and mean databases will lag.
To opt for a flight profile of massively increased danger - and then having to totally rely on a multiple crew trying to use complex systems properly, (eg radar open to misinterpretation) and fallible databases and EGPWS, to keep safe, is just nuts.
Don’t get me wrong – all the risk factors identified need addressing as soon as possible. But to me the immediate safety actions should be reviewing the approach profiles, particularly vertical, that crews use in situations like this. Clearly if you’re looking for a bloke on a surfboard (and great job btw, SAR Prestwick) flying at 200ft is perfect. But not for 10 miles for an approach at night to a refuelling base. And the needing to be 200ft to be VMC just doesn’t add up here – (a) I don’t think many of us think they were, and (b) the chances were always going to be high of areas of further reduced cloud-base – what were they going to do then? Descend further? Climb into it and go IMC? Turn back?
Clearly the crew chose to use this approach type. Following the investigation, it will be very interesting to see what light is shed on just why.