AS332L2 Ditching off Shetland: 23rd August 2013
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That's the way the Puma was designed. Counterintuitive maybe but it worked. Set a pitch and fly on the cyclic, I know having attended No 1 Puma course in the RAF, we didn't have multi-axis AFCS's in those days though.
Avoid imitations
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Either method can work but obviously you have to fully understand what the autopilot is doing, and what it is not doing.
I often fly off airfield letdowns, i.e. non-precision approaches. I find it more intuitive and more accurate to let the airspeed hold do it's job and to initiate and subsequently control the ROD with collective.
At MDA (actually just before) I level off the aircraft using collective. It helps to know the required S+L Tq setting for the IAS being flown but this was already in use at TOD, then I activate "ALT" hold mode. That way the IAS will not decrease under influence of the AP. If I am visual, I then disengage the Alt and Heading modes together using the release button and fly with all AP modes out. If not visual, with the ALT mode engaged, lowering the lever again will cause the IAS to be decreased.
I prefer this method because levelling off using the VS mode requires hand swapping on the cyclic at a critical stage (to reset the VSI bug to zero). This is in addition to raising the collective to avoid a reduction of IAS as the aircraft levels itself off.
I often fly off airfield letdowns, i.e. non-precision approaches. I find it more intuitive and more accurate to let the airspeed hold do it's job and to initiate and subsequently control the ROD with collective.
At MDA (actually just before) I level off the aircraft using collective. It helps to know the required S+L Tq setting for the IAS being flown but this was already in use at TOD, then I activate "ALT" hold mode. That way the IAS will not decrease under influence of the AP. If I am visual, I then disengage the Alt and Heading modes together using the release button and fly with all AP modes out. If not visual, with the ALT mode engaged, lowering the lever again will cause the IAS to be decreased.
I prefer this method because levelling off using the VS mode requires hand swapping on the cyclic at a critical stage (to reset the VSI bug to zero). This is in addition to raising the collective to avoid a reduction of IAS as the aircraft levels itself off.
HC.
I'm kind of in agreement with crab, but open to discussion. How do you fly the other way round? Set a power setting on collective and then set a speed either side of the curve to get a rate of climb or descent? Not something I'm familiar with. Could you explain?
I'm kind of in agreement with crab, but open to discussion. How do you fly the other way round? Set a power setting on collective and then set a speed either side of the curve to get a rate of climb or descent? Not something I'm familiar with. Could you explain?
The simplest example is when you are cruising at max continuous power. That means you can't raise the collective any more. So if the heli starts to descend, you have to raise the nose slightly and accept a reduction in airspeed. You are in fact flying altitude on the cyclic and leaving the power alone.
In the context of autopilots, when you engage altitude hold on a 3 axis machine, or a 4 axis machine being flown in 3 axis, the altitude hold goes onto the cyclic (assuming you are not going too slowly). It all seems totally normal to me!
In a 3 axis machine flying a non-precision instrument approach you could chose either IAS or VS / ALT.A on the cyclic. The former has the advantage of ensuring an L2-scenario doesn't develop. The latter has the advantage of allowing precise control of the vertical profile including level-off at MDA. Which is best I think depends on a couple of factors: How fast you intend to go, and which is the most important parameter.
So for an approach flown fast, well above Vy, you might choose to couple to VS/ALT.A . For an ILS, where glideslope is the most important parameter to be precise with, I would want to couple it to the autopilot (presuming the autopilot was good at flying it!). However the pitfall in the event of a go-around is that you now have a climb being demanded on the cyclic, you must remember to raise the collective or risk running out of speed, and if you go OEI the most important parameter to have the AP controlling is the airspeed, at Vy.
For an approach flown near to Vy, I would definitely want to couple to IAS and control the vertical mode with the collective.
So there is no one-size-fits all answer. But the pilot of a modern autopiloted helicopter who can't make a sensible decision about which mode to couple and which to fly, and follow it through to a safe conclusion, is incompetent. Just like a pilot who can only turn right, but not left!
Whilst I am rambling on, also consider the interchangability of kinetic and potential energy 1/2 MV^2 = MGH. Cancelling out the constants M and G gives us 1/2 v2 proportional to H. Note the speed squared term. So at low speed, a modest change of speed has a small effect on altitude. At high speed, a very small change in speed (very small change in pitch attitude if you like) has a huge effect on altitude. So if you are intent on maintaining a certain speed with the cyclic whilst doing 150kts, tiny changes in cyclic will induce high vertical speeds that the collective is probably unable to contain, or at least it will be very uncomfortable if you try. It is just not the right way to fly at high speed because it doesn't work!
212man,
I worked on a 3-axis A/P that was fitted both to the Alouette III and the 212... but that goes back to the mid-seventies, so I reckon I'd better stay out of the discussion !
I worked on a 3-axis A/P that was fitted both to the Alouette III and the 212... but that goes back to the mid-seventies, so I reckon I'd better stay out of the discussion !
1/2 MV^2 = MGH
Out of interest, all twin engine mil training at DHFS has been on the Griffin which has a similar autopilot such that instrument approaches are flown using cyclic to control RoD and collective essentially controls speed.
Now the basic and advanced training for all other approaches is cyclic for speed and collective for RoD.
So all our recently trained pilots have managed to cope with both concepts and are specifically checked on their IRTs to ensure the 'counter-intuitive' method is understood and correctly managed.
Guess what? It all comes down to training!
Now the basic and advanced training for all other approaches is cyclic for speed and collective for RoD.
So all our recently trained pilots have managed to cope with both concepts and are specifically checked on their IRTs to ensure the 'counter-intuitive' method is understood and correctly managed.
Guess what? It all comes down to training!
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You can press as many buttons as you wish,but in my time of flying in the north sea the non handling pilot should be keeping a very good eye on airspeed/rate of descent and rad alt,looking for a visual at mdh ,,and did no one see the sea appear below and infront of them
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micraman
Think they now call him the Pilot Monitoring ...... but surely the PF is the primary man scanning the instruments - PM backs up whilst also head in and out searching for the visual clues. I would reckon the loss of control occurred IMC ? .... so imho they probably did see the sea below and in front.
Think they now call him the Pilot Monitoring ...... but surely the PF is the primary man scanning the instruments - PM backs up whilst also head in and out searching for the visual clues. I would reckon the loss of control occurred IMC ? .... so imho they probably did see the sea below and in front.
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212 man, HC and crab,
I think we're all in agreement that few things in a helicopter are truly intuitive, there is still machinery, the roots of which are in the 70s and that whose roots are close to the turn of the new Millennium, flying and any pilot who wishes to be considered a 'professional' needs to stick his nose in the books at regular intervals and do some homework. If the only time he/she does this is before an annual sim ride then, as Timothy Cratchit said, 'God bless us all' (or God save us all as I say
)
I think we're all in agreement that few things in a helicopter are truly intuitive, there is still machinery, the roots of which are in the 70s and that whose roots are close to the turn of the new Millennium, flying and any pilot who wishes to be considered a 'professional' needs to stick his nose in the books at regular intervals and do some homework. If the only time he/she does this is before an annual sim ride then, as Timothy Cratchit said, 'God bless us all' (or God save us all as I say
)
Slightly disappointing in that there isn't an awful lot of new stuff. Once again I notice that the airspeed, whilst very low at 35 kts, was still quite recoverable when the co-pilot called it. But it took 8 seconds to reach full power by which time it was too late.
The engines on an L2 etc accelerate very quickly, you could probably go from 24% to 100% Tq in 2 seconds and thus have recovered the situation. Less than 2 seconds with a bit of rotor droop.
I do wonder to what extent the reluctance to make a rapid collective movement was linked to a desire not to reveal to the passengers that something had gone badly wrong. Is it in part, at even a subconscious level, a result of the culture of passengers complaining about, and pilots having to explain, the slightest deviation from normality, with big stick oil company constantly banging the "we pay your salary so you are totally accountable to us for every minutia of your misdeeds"?
ps, is it just me, or is everyone seeing another 2 phantom pages on this thread (117 and 118) that cannot be accessed? Edit: they've disappeared now!
The engines on an L2 etc accelerate very quickly, you could probably go from 24% to 100% Tq in 2 seconds and thus have recovered the situation. Less than 2 seconds with a bit of rotor droop.
I do wonder to what extent the reluctance to make a rapid collective movement was linked to a desire not to reveal to the passengers that something had gone badly wrong. Is it in part, at even a subconscious level, a result of the culture of passengers complaining about, and pilots having to explain, the slightest deviation from normality, with big stick oil company constantly banging the "we pay your salary so you are totally accountable to us for every minutia of your misdeeds"?
ps, is it just me, or is everyone seeing another 2 phantom pages on this thread (117 and 118) that cannot be accessed? Edit: they've disappeared now!
Last edited by HeliComparator; 23rd Jan 2014 at 10:32.
The phantom pages seem to be happening regularly across pprune. Sometimes they simply don't exist but at other times there are posts on pages that are not accessible until they are displayed below a reply window.
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At the bottom under the pink recommendations box, it shows a publish date of 18 October 2013. Is this latest bulletin really that new?
HC, whether it's your operating company or the oil company, when you are on the clock, you are accountable for your time, just like we all are.
I understand that its uncomfortable when Sky Gods are asked a question by a pesky passenger but that's what you are paid to do. Perhaps EI and interpersonal skills should be part of your selection process like they are for most careers.
HC, whether it's your operating company or the oil company, when you are on the clock, you are accountable for your time, just like we all are.
I understand that its uncomfortable when Sky Gods are asked a question by a pesky passenger but that's what you are paid to do. Perhaps EI and interpersonal skills should be part of your selection process like they are for most careers.
TM my point was a genuine one. If you have an interest in flight safety, as is implied by your general demeanour on here, you shouldn't dismiss it so glibly. Or perhaps you don't really understand the human factors behind my point?
Perhaps you have a better explanation for why the pilot, having initiated recovery action, did it so slowly and gently that a crash resulted?
Perhaps you have a better explanation for why the pilot, having initiated recovery action, did it so slowly and gently that a crash resulted?
HC,
If a Pilot in Command of a Passenger carrying helicopter has developed a mindset such as you have suggested possible....there is something sadly missing in his Helicopter Pilot DNA!
Imagine the guy realizing things have gotten all pear shaped and very dangerously close to the water....with a high rate of descent showing....alerts going off in his Ears....the Copilot telling him about too....and the SOB would first think through whether his abrupt raising of the Collective might cause the SLF to complain or question what happened?
You cannot be serious?
You reckon those same Passengers who wind up in the water because of his indecision might be prone to file a slight objection?
If a Pilot in Command of a Passenger carrying helicopter has developed a mindset such as you have suggested possible....there is something sadly missing in his Helicopter Pilot DNA!
Imagine the guy realizing things have gotten all pear shaped and very dangerously close to the water....with a high rate of descent showing....alerts going off in his Ears....the Copilot telling him about too....and the SOB would first think through whether his abrupt raising of the Collective might cause the SLF to complain or question what happened?
You cannot be serious?
You reckon those same Passengers who wind up in the water because of his indecision might be prone to file a slight objection?
Once again I notice that the airspeed, whilst very low at 35 kts, was still quite recoverable when the co-pilot called it. But it took 8 seconds to reach full power by which time it was too late.
The engines on an L2 etc accelerate very quickly, you could probably go from 24% to 100% Tq in 2 seconds and thus have recovered the situation. Less than 2 seconds with a bit of rotor droop.
The engines on an L2 etc accelerate very quickly, you could probably go from 24% to 100% Tq in 2 seconds and thus have recovered the situation. Less than 2 seconds with a bit of rotor droop.
It would appear no one....including George!
Personally, I think HeliCompator is onto something here, whether we're willing to admit it or not.
I'm certain that every pilot on this board privately considers himself to be the best pilot to ever be certified to fly helicopters. SASless certainly does. And I'm equally sure that every pilot on this board arrogantly thinks that he/she would *never* be subject to the subtle psychological issues and pressures that HC brought up in his post. Moreover, every pilot here probably assumes that every other pilot should and would always react the same way he/she would: appropriately and in a timely manner.
The trouble is, we're *not* all Chuck Yeager or Chuck Aaron. We're *not* all the best of the best...other than in our minds. I know that for SASless (and surely others as well) it's simply preposterous to consider that the PF of the Puma wouldn't have immediately recognized their peril and yanked in an armload of power and saved the day. Because that's what we all would have done, right?
But he did not. And so we are left to wonder why not? Was he that clueless, that weak of a pilot? I'd guess not - weak or poor pilots generally don't rise to the level of AS-332 captain. No, there had to be some other reason he was so slow on the power increase.
Me, I think HC's premise is plausible.
I'm certain that every pilot on this board privately considers himself to be the best pilot to ever be certified to fly helicopters. SASless certainly does. And I'm equally sure that every pilot on this board arrogantly thinks that he/she would *never* be subject to the subtle psychological issues and pressures that HC brought up in his post. Moreover, every pilot here probably assumes that every other pilot should and would always react the same way he/she would: appropriately and in a timely manner.
The trouble is, we're *not* all Chuck Yeager or Chuck Aaron. We're *not* all the best of the best...other than in our minds. I know that for SASless (and surely others as well) it's simply preposterous to consider that the PF of the Puma wouldn't have immediately recognized their peril and yanked in an armload of power and saved the day. Because that's what we all would have done, right?
But he did not. And so we are left to wonder why not? Was he that clueless, that weak of a pilot? I'd guess not - weak or poor pilots generally don't rise to the level of AS-332 captain. No, there had to be some other reason he was so slow on the power increase.
Me, I think HC's premise is plausible.
HC,
If a Pilot in Command of a Passenger carrying helicopter has developed a mindset such as you have suggested possible....there is something sadly missing in his Helicopter Pilot DNA!
Imagine the guy realizing things have gotten all pear shaped and very dangerously close to the water....with a high rate of descent showing....alerts going off in his Ears....the Copilot telling him about too....and the SOB would first think through whether his abrupt raising of the Collective might cause the SLF to complain or question what happened?
You cannot be serious?
You reckon those same Passengers who wind up in the water because of his indecision might be prone to file a slight objection?
If a Pilot in Command of a Passenger carrying helicopter has developed a mindset such as you have suggested possible....there is something sadly missing in his Helicopter Pilot DNA!
Imagine the guy realizing things have gotten all pear shaped and very dangerously close to the water....with a high rate of descent showing....alerts going off in his Ears....the Copilot telling him about too....and the SOB would first think through whether his abrupt raising of the Collective might cause the SLF to complain or question what happened?
You cannot be serious?
You reckon those same Passengers who wind up in the water because of his indecision might be prone to file a slight objection?
Like TM, you dismiss a possible human factor without proposing any other explanation. Rather negative, but of course such ideas don't fit your Vietnam vet mindset.
Regarding your last sentence, it seems you are proposing that such a possibility is not investigated lest it upset some of the passengers who ended up in the water. Surely you are demonstrating EXACTLY the mindset to which I am referring. I'm surprised you can't see it.
HC about SAS:
I'm not.
Regarding your last sentence, it seems you are proposing that such a possibility is not investigated lest it upset some of the passengers who ended up in the water. Surely you are demonstrating EXACTLY the mindset to which I am referring. I'm surprised you can't see it.