Last but certainly not least… the more one flies, the more one exposes himself to the risk. Of making one mistake, two mistakes, etc. Armchair flyers will have super safe flying records for sure.
Well you don’t need to insure hull-value if you are a cautious pilot, the majority of armchair pilots with safe flying records should not buy hull insurance value 
Financially, you have to fly often to make money on your insurance premium
Insurance rarely price risks at granular levels as they aim to aggregate things across a diversified homogeneous pool of pilots (that is how insurance maths to work), they can still decide who to insure and who they don’t insure based on granular criteria
The turbo controller is actually quite precise and 3.3 inch overboost does not just happen. The setup of this engine was
completely wrong. A clear maintenance problem
That may well be true for he PA46, I wouldn’t know. But it certainly wasn’t true on my now-sadly-ex TR182. There was a kind of safety valve thing downstream of the turbo that would limit MP to 31". It’s not something you really want to test for obvious reasons, but on the odd occasion when I did overboost for a couple of seconds it didn’t work. It had been replaced least twice, to no effect. A long, long time ago I way overboosted, tired on the last go-around of a series of instrument approaches, and it was fine with going up to 40" in the few seconds it took me to realise and correct.
The other thing to note is that in Europe there is limited expertise when it comes to turbos.
I’ve known multiple TB21 owners with long downtime (up to 1 year) due to turbo problems and nobody being able to solve it, and this wasn’t just the UK. IIRC, the TB21 turbo is a US product (Tornado Alley?) which Socata bought in and certified in-house. There is something delicate about the adjustment.
So I can fully see a turbo owner avoiding anybody touching the turbo.
Airborne_Again wrote:
The purpose of an accident investigation is not just to explain what happened but also why it happened
Yep, and that should be it.
Extreme speculation example: had he succeeded in taking off, he could have crashed on the motorway on top of a fully loaded bus, which was followed by truck filled with highly explosive substances… IF. IFs.
In the present case the AAIB made no effort in calculating, or replicating, under the same circumstances and using all the correct procedures as in full rated power, standing take-off, optimal use of flaps (different opinions in the some of the posts above), etc, to demonstrate if the TORA was sufficient for a lift-off to not.
Yes, it is not relevant to explain this accident case, but could underline the hazardous decisions made by the pilot in question.
Airborne_Again wrote:
Maybe insurance rates should be based also on aircraft flight time?
or better yet movements? Most accidents/incidents happen in the take-off or landing phase, so why not? I would say the risk for an aircraft gets bigger the more it flies… sitting on the ground one does not even need liability for it.
Different matter with pilots, the plot is more difficult, age, experience and recency, kind of flying, etc, all are at play. I’m certainly no expert at how the insurances look into this kind of matter, though being on the hunt for a new contract right now told me a couple of things…
Any insurer reading these lines and willing to share their hindsight?
Manifold pressure on turbo engines… I don’t know the PA46, but I’m very surprised too that the MP limit can be exceeded at all, and is not regulated on this kind of airplane.
I happened to have flown a few hours in a venerable Seneca which had no wastegates. It is a long time ago, but IIRC the procedure was to set the power just below the MAP warning during the standing take-off. As the airplane accelerated, the MAP built up and usually the warning came on, which in turn had one constantly reducing the power during the take-off roll and initial climb. Good fun on a twin
I don’t particularly disagree with you Dan on anything but GA reports will nearly always contain a load of BS – simply because there is no FDR or CVR, or even a QAR
I’ve read hundreds of GA accident reports.
Politics come into it heavily. In some (most) countries the reports avoids criticism of “the system” e.g. ATC or airspace policy. In the UK for sure they steer miles away from these topics even if they are blindingly obvious. If it is a large death toll airline crash it gets much worse, and in some countries the reports are quite ridiculous.
Maybe we could refrain from personal speculation here?
Sorry. I was talking as a former dispatcher. And there it is perfectly clear that if there are no numbers for something, it is not done.
So if you don’t have a Flaps 10 take off table, no take off with flaps 10. And so on.
We all know that due to the miserable quality of GA POH’s we can’t have those standards in GA, otherwise most airplanes would e.g. loose the capability to operate from grass or wet runways or similar. So we are often relegated to “test pilot” territory when it comes to stuff which the POH does not cover.
E.g. nobody in GA would stop operating if QNH goes above a value the altimeter can cover, but airlines regularly do that.
So this take off was not covered.
As for accident reports: I have to read through a lot of them due to some work I do. And all of them include “speculation” often because they have nothing else to go on, particularly in GA. Even the infamous Ju Air report includes quite a lot of it, not least on the subject of former airline and military pilots, some of which insulting. There were cases where accident reports were retracted after it was found that they were factually wrong based on pure speculation. And then you have places where accident reports are co-written by the justice department or even told what to write.
I used to be a big believer in the neutrality of TSBs, no longer. Having said that, the AAIB always was one of the TSBs to be trusted more than most others. In this particular case, yes there was some speculation, but they got the gist pretty neatly. Apart from refraining from undue recommendations. I know TSB’s who in this kind of scenario would probably suggest grounding former airline pilots or heaven knows what they come up with. The fall out of some accidents in recent times were WAY over the rational top. Apart, some reports in recent years are pure political fabrications to cover the backside of nationally important airlines and aircraft manufacturers. Dead pilots tell no tales.
But in this case I would not say the commander of this airplane has been treated unfairly.
In this case, we have a 31000 hour guy missing that he was overloaded dangerously and unable to set proper take off power. One could argue that this may well be a consequence of years of being served a load sheet and having automatisation setting thrust. The probability that this is causal in the accident may be 50/50 but the AAIB to their credit refrains from this kind of speculation.
I don’t know the PA46, but I’m very surprised too that the MP limit can be exceeded at all, and is not regulated on this kind of airplane.
If I understand some posts earlier it should not happen. Most turbos now have automatic wastegates.
The Seneca as you mention did not have it, so the scenario you recall so vividly is exactly the same as in this case, only it was expected. The Seneca II is an airplane with a fixed wastegate, as opposed to an automatic one, so it gets constantly overboosted on take off. And fiddling with the throttles during take off has left a lasting impression on many pilots for turbos, often to the effect that exactly this scenario could happen.
You probably also recall the pre-FADEC jets, they were the same, which is why you almost always had the PNF or before the FE set the actual power. You could seriously damage e.g. the 747 classic engines if you firewall the throttles. Same with MD80 and others. The fadec engines of todays airplanes have greatly reduced this risk.
Mooney_Driver wrote:
it should not happen. Most turbos now have automatic wastegates.
Even with automatic wastegates, hamfisted throttle advance can lead to temporary overboost. Any decent differences training on a turbo aircraft should cover that. The proper technique for this is to stop advancing the throttle or even back off a little, allow the wastegate to correct, and then slowly advance again to full throttle. This is different from a fixed / mechanical wastegate where you back off to 1-2 inches MAP below redline and leave the throttle there.
For the paricular malibu engine in the accident, there even is a supplementary service publication (SSP-400) which contains the following text:
“The engine power setting for takeoff is 42 in. MAP, 2500 RPM, Full Rich Mixture. Observe the manifold pressure redline. It is not unusual to experience an overboost of up to 2 in. MAP with cold oil or on the first takeoff of the day. During cold conditions, the throttle movement rate can exceed the capability of the turbocharger controller to regulate manifold pressure. The overshoot condition can normally be prevented by interrupting the throttle advance momentarily several inches below rated manifold pressure. This allows the cold control system to catch up with the throttle movement”
Dan wrote:
In the present case the AAIB made no effort in calculating, or replicating, under the same circumstances and using all the correct procedures as in full rated power, standing take-off, optimal use of flaps (different opinions in the some of the posts above), etc, to demonstrate if the TORA was sufficient for a lift-off to not.
They did calculate that with full power and according to POH figures (extrapolated for the overweight with the assistance of the manufacturer) the distance to 50 ft would be 3150 ft while the distance from the start of the takeoff roll to obstacles (trees) was 2700 ft. It is possible that with full power and a non-standard takeoff procedure (as suggested here), the aircraft could have cleared the obstacles. But the PIC didn’t follow even follow thePOH procedures and had approximately 85% power so what would have been the point of any further calculation or replication?
What I take with me from the report, is how the “commander” seemed to let the perceived pressure cloud his judgement. Not least because it adds to the large number of other accidents where this also seems to be a likely root cause. I certainly do not consider myself immune, and I like to be reminded of that trap.
I think the report is fair. While the analysis obviously should not be based on unnecessary speculation, I do not consider the small amount of speculation in this report unappropriate, and I think it serves to put the decision to abort in perspective. And +1 to everything @Mooney_Driver wrote in #36.
