G-BOMG (Scottish Air Ambulance Islander Crash off Ayrshire West Coast (WNWest of Campbelltown)

from UK AAIB link
Page 43 [51 of 81]

It's really all about this. It is so easy for a single pilot operation to lose the plot at night in weather. It just takes a moment's distraction or inattention to enter an unrecoverable  and divergent unusual attitude.

The UK CAA accepted the recommendation but then decided not to act upon it (see page 44 [52 of 81)for their silly reason).
_________________________________________________________________________________ ____________________
The cause of his ditching is also possibly due to carburettor icing. This claims many pilots who just tend to forget about it. The conditions certainly demanded it but it wasn't being used. That type icing can be insidious (the power simply not being there when you go for it).The possibility of carby ice affecting both engines equally and simultaneously is very high.

______________________________________________________________________________________________________
The thing to remember is that if the conditions are conducive to carby ice forming, it WILL form in the carby throat. The only question is then whether enough will form to choke the gas flow and affect the engine's power output. In a low power descent Instrument Approach you're not likely to find out until you go to apply power. The surprise factor is then going to make carby icing possibly the last thing that you think of.

The other nasty aspect of carby icing is that by the time you get the symptoms (usually of power loss) it's too late. Why? because the engine by then isn't capable of generating sufficient heat fast enough to melt the icing build-up.A selection of HOT immediately after becoming aware of carby icing can also lead to a rich cut if the throttle is anyways OPEN (Ice dislodges and blocks all airflow past the venturi throat).

Although the report canvasses the possibility of carby icing, it's also given it insufficient analysis (i.e. no mention at all) as a probable cause.
_________________________________________________________________________________ ____________________

Good call, but wouldn't have helped if it was carby icing stuffing both engines simultaneously
_________________________________________________________________________________ ____________________
Almost unbelievably there's nothing whatsoever in the findings or causal factors about the possibility of carby icing having knocked out any power re-application from either engine. A double engine failure from carby icing is certainly a possibility. The engine doesn't really "fail" as such. It keeps running at low power but fails to produce any power on demand. I've seen that a number of times after a protracted descent in very humid conditions on a piston-powered machine without fuel injection.

The crash position was around about where the pilot would have been going for power in the conditions (i.e. he needed a break-out of cloud at around 1000ft to be able to legally circle for r/way 25 - his expressed intention.). So he needed to level off at 1000ft. That's about when he would've found the power on demand just wasn't there. At that point he'd have been checking fuel and even if he had thought of carby icing as a cause, it wouldn't have made any difference at that late stage.

james.smith@iinet.net.au