PPRuNe Forums - View Single Post - Cirrus down Gundaroo, 06/10/23
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Old 8th Oct 2023, 18:59
  #129 (permalink)  
FullMetalJackass
 
Join Date: Jan 2021
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Originally Posted by Lead Balloon
That’s some very interesting stuff, FMJ.

Yet a Cirrus salesman contributed to rather than busting that myth, as a consequence of this event which resulted in this unwelcome garden ornament.
Firstly, I said that when stalling straight and level, the Cirrus will not drop a wing. That instance, the pilot was banking at 25°, performing the fabled base to final turn with associated stall / spin. Most planes would drop a wing and enter a spin if the plane is not co-ordinated. However it might interest you to note that EASA considers the SR 20 / 22 aircraft to be one of the few truly spin resistant aircraft to have been certified - not spin immune, but spin resistant.

However, let's go back to that incident with the salesman / pilot. Why did the Pilot fail to recover? Because, according to the passenger who was also a pilot. he applied pro spin rudder rather than anti. Had he acted correctly, he would have had no issue. However he did at least remember his hard deck and pulled before it became too late.

Originally Posted by Lead Balloon
This had me scratching my head:Then why did you mention circumstances in which a pilot “slumps across the controls, locking them” – your words – in this thread? Surely you comprehended that the uninformed, hungry-for-facts people out there would take that as you suggesting that as an explanation for the tragedy. Surely.
You might recall your exact words were "How does sudden pilot incapacitation result in an aircraft plummeting to the ground?" You didn't refer to a Cirrus but to an aircraft hence I answered. Go check what you wrote and you will see you did NOT specify a Cirrus plummeting to the ground otherwise I would not have made such a suggestion. Please check your original post.

Originally Posted by Lead Balloon
As to the rest: I get it. I get it that someone needs to run interference to protect the interests of the aircraft manufacturer and distributors and maintainers, while there’s all the swirling publicity and emotion in the wake of an awful tragedy. I get it. And it may turn out that this tragedy is the consequence entirely of the pilot and not a serviceable aircraft.

My original post was in response to those who decided to leap to the keyboard and post that the cause of this tragedy was likely pilot incapacitation or – and it makes me sick to even contemplate it – to suggest some deliberate action by the pilot. Before the smoke had lifted on the site of the tragedy.

If you want to keep pressing for pilot incapacitation, that’s your choice, as is mine to continue suggesting different possibilities.
Firstly,. I refuse to accept it was deliberate action, let me get that part out of the way. However history shows that Cirrus don't typically have wing spar issues like certain other brands therefore a catastrophic failure in the absence of CBs is unlikely. Their BRS system has been proven as reliable over the decades, the two issues you refer to were caused after the change to electronic ignition which was then rectified by an SB. This aircraft would have had its chute repacked last year so was not susceptible to spurious ignition. I therefore rule out any uncommanded activation or inability to pull - unless the owner flew with the safety pin still in the handle - some do, you know.....

I'm not "running interference for the manufacturer" because I know from first hand experience how good those aircraft are and what it takes to cause them to fail. I'm a fan of Cirrus aircraft - except, perhaps, for their pricing policy, especially of the costs for BRS repacking...You, on the other hand, appear to be searching for reasons which would require multiple issues happening at the same time, allowing the holes in the swiss cheese to line up whereas I am merely saying that the most likely cause is an aircraft being hand flown in moderate icing - the GAFOR said that clouds above freezing level inferred moderate icing - with an incapacitated pilot causing it to ice up and stall.

At the end of the day, the aircraft went from cruise climb to a rapid descent - within 15 seconds his vertical speed had changed from 800 feet upwards to 3700 feet downwards. The only way I have seen a light aircraft change that rapidly without a commensurate gain in airspeed is either structural failure - which has been ruled out so far - or for the plane to stall - and knowing how well these aircraft are built, I cannot believe a mechanical defect could force a plane into such a 90° nose down dive within 15 seconds. Perhaps you can think of such a failure mode - otherwise I remain by my belief that the aircraft stalled due to ice, that was the start of the incident.

The question remains: Why did the pilot not react? Why did he not recover or at least pull the chute? The most logical solution is - because he couldn't.... I find it amusing that you are opining that the plane could become inverted, that CAPS could be deployed which then became tangled with the aircraft..... Sure, this theoretically could happen but it begs the question: what caused the upset? How does an SR22, climbing along suddenly become inverted and, within 15 seconds, start descending at nearly 4000fpm??? If the accident aircraft had become inverted and wrapped up in its Chute, the pilot would have known that it's effectively game over, I would have expected him to make a call.

Originally Posted by 43Inches
You just need to read the CAPS event webpage that LB posted earlier to know that statement is untrue. There's been a number of CAPS deployments in situations where they should have just landed, instead they panicked and pulled the chute. We are talking about bog standard PPLs here in most cases, not air force test pilots and ex NASA shuttle pilots. One fatal was at high speed and altitude over the rockies, with the predictable outcome that the chute separated and the aircraft speared in almost vertical. Another one had investigation results that talk about the operational limits of CAPS, maximum speeds, but, also maximum attitude, bank angle and pitching/rolling motions to prevent possible entanglement. The outcome was that the chutes effectiveness would be suspect outside of relatively slow, upright, level flight.
Historically speaking, Cirrus had a worse fatality rate than similar aircraft so COPA initiated a "pull early, pull often" mantra - which was basically to tell them: You have the chute, use it. Ridicule came because pilots were accused of pulling when they flew a tank ran empty rather than trouble shooting the issue within the time (altitude) available to them. However, typically the training at CPPPs is, if you have an issue in cruise at, say, 8000 feet, to first trim to maintain airspeed, point yourself towards the nearest airfield / suitable landing spot then trouble shoot the issue whilst remaining aware of the lowest deployment altitude. If a landing is not 100% assured when a few hundred feet above your hard deck, pull CAPS.

The fatal over the rockies was IIRC, a pilot caught in icing and he deployed CAPS after exceeding more than 180KTAS - here, the pilot was nowhere near this sort of airspeed. Concerning operational limits of CAPS, the question is: how does a plane flown by a competent and current IFR rated pilot suddenly experience an upset which, if CAPS was deployed, would cause entanglement around the aircraft? How does the plane invert itself?
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