Helicopter Height-Velocity (H-V) limitations
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g..wiz great answer you are spot on
are you familiar with George Bernard Shaw asking a Lady on a train if she would 'sleep with him' for a hundred million pounds (inflation adjusted)? she said "yes", so then he said (to cut a long story short) that he had established that she was a whore but now they were just haggling about the price!
In the same way we should quantify where the threshold is. It certainly is not 20 to 1, you say it is 20 to 15 ... the threshold is somewhere, and a little logic and maths can help us find 'the right answer', it is not an absolute.
We are smart and we should apply some science and logic, not just knee jerk reactions and gut-feel We can do better than that.
Maybe exposure, maybe even a B3 with 2 pax on board, floats, emersion suits, modern avionics, sliding doors and dingies is justifiable? Maybe? Many more pilots employed for starters.
Exposure can be right, there's a level at which it works.
(despite what the AW salesman(?) bpaggi says)
thanks for answering the point, much respect, and i don't mean to be rude
are you familiar with George Bernard Shaw asking a Lady on a train if she would 'sleep with him' for a hundred million pounds (inflation adjusted)? she said "yes", so then he said (to cut a long story short) that he had established that she was a whore but now they were just haggling about the price!
In the same way we should quantify where the threshold is. It certainly is not 20 to 1, you say it is 20 to 15 ... the threshold is somewhere, and a little logic and maths can help us find 'the right answer', it is not an absolute.
We are smart and we should apply some science and logic, not just knee jerk reactions and gut-feel We can do better than that.
Maybe exposure, maybe even a B3 with 2 pax on board, floats, emersion suits, modern avionics, sliding doors and dingies is justifiable? Maybe? Many more pilots employed for starters.
Exposure can be right, there's a level at which it works.
(despite what the AW salesman(?) bpaggi says)
thanks for answering the point, much respect, and i don't mean to be rude
AnFi, Congratulations. You discovered another AW salesman. Why don't you apply for a job with the Mossad?
https://www.ainonline.com/sites/defa...posium2015.pdf
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Mr Paggi
A) you are an AW employee !
B) you are a salesman ! (selling HOGEFAP (Hover Out of Ground Effect Fly-Away Performance)
C) your technical arguments are susspect (selling HOGEFAP) because they are likely to support the interests of your employer
D) there is nothing wrong with my technical understanding, thank you.
Itally has a very fine heritage of design (Savoia, Macchi, Piagio, Ferarri etc etc, way groovier that the Germans or French ever managed etc how can you tollerate allowing that heritage to be sold out to bureaucrats, wtf do they know about design? You know better, or at least you should!)
Why don't you honestly answer the question about 'exposure' ?
It CAN be safer, true?
What's your answer in the example? If you want then replace 6,1,3,2 with w,y.x and z and then say where you think the safety threshold is? but the point is it IS somewhere, right?
Perhaps even a B3 with 2 pax, 2 dingies and floats and 2 sliding doors would be safer?
More pilot employed also.
We can't have aviation design poilcy made from commercial interest nor amateur guesswork, unless you want protectionism?
Don't disparage my technical credentials if you don't know what they are pls.
you have been
AnFi'd
A) you are an AW employee !
B) you are a salesman ! (selling HOGEFAP (Hover Out of Ground Effect Fly-Away Performance)
C) your technical arguments are susspect (selling HOGEFAP) because they are likely to support the interests of your employer
D) there is nothing wrong with my technical understanding, thank you.
Itally has a very fine heritage of design (Savoia, Macchi, Piagio, Ferarri etc etc, way groovier that the Germans or French ever managed etc how can you tollerate allowing that heritage to be sold out to bureaucrats, wtf do they know about design? You know better, or at least you should!)
Why don't you honestly answer the question about 'exposure' ?
It CAN be safer, true?
What's your answer in the example? If you want then replace 6,1,3,2 with w,y.x and z and then say where you think the safety threshold is? but the point is it IS somewhere, right?
Perhaps even a B3 with 2 pax, 2 dingies and floats and 2 sliding doors would be safer?
More pilot employed also.
We can't have aviation design poilcy made from commercial interest nor amateur guesswork, unless you want protectionism?
Don't disparage my technical credentials if you don't know what they are pls.
you have been
AnFi'd
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AnFI,
about your
I have to admit that you are very clever to ridicule my thoughts.
So let me explain the rationale behind my example
15 Pax vs 20 shows that flying PC1 with a medium helicopters, like those operated in the North Sea, does not increase significantly the number of flights: 4 flights instead of 3 for moving 60 pax. The increment is 1 over 3 equal to 33%.
While in your example, 2 pax vs 6, applicable to a B206, the increment is 2 flights over 1 equal to 200%.
So I was not playing with numbers but only trying to demonstrate that
"no exposure" does not increase dramatically the operational costs if you compare with the costs , in human life and economic, associated with a potential accident.
about your
In the same way we should quantify where the threshold is. It certainly is not 20 to 1, you say it is 20 to 15 ... the threshold is somewhere, and a little logic and maths can help us find 'the right answer', it is not an absolute.
So let me explain the rationale behind my example
15 Pax vs 20 shows that flying PC1 with a medium helicopters, like those operated in the North Sea, does not increase significantly the number of flights: 4 flights instead of 3 for moving 60 pax. The increment is 1 over 3 equal to 33%.
While in your example, 2 pax vs 6, applicable to a B206, the increment is 2 flights over 1 equal to 200%.
So I was not playing with numbers but only trying to demonstrate that
"no exposure" does not increase dramatically the operational costs if you compare with the costs , in human life and economic, associated with a potential accident.
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Gee Mr Wizz
I definately mean not disrespect, quite the opposite infact, I have a lot of respect for you, like wise for Paggi really, although we have to be aware that it is difficult for him to be objective since his job is to promote a particular technical solution.
A serious understanding of these concepts is vital.
The point about the 200% against the 33% is we do accept that there is a number. Now we have to look at whether that number is important or unimportant.
I would like to suggest that it is more important than is obvious.
We could simply take the proportion of the total losses that are caused by engines and divide by the total losses.
If this number were, say then 50% then your 33% deal would be worth it.
If that number is 5% then it is not worth it. We have then made it more dangerous in the misguided attempt to make it safer.
It is an example of too much emphasis on egines, at the expense of weight/payload that would be available to spend on higher yielding safety features. (like fuel maybe)
I definately mean not disrespect, quite the opposite infact, I have a lot of respect for you, like wise for Paggi really, although we have to be aware that it is difficult for him to be objective since his job is to promote a particular technical solution.
A serious understanding of these concepts is vital.
The point about the 200% against the 33% is we do accept that there is a number. Now we have to look at whether that number is important or unimportant.
I would like to suggest that it is more important than is obvious.
We could simply take the proportion of the total losses that are caused by engines and divide by the total losses.
If this number were, say then 50% then your 33% deal would be worth it.
If that number is 5% then it is not worth it. We have then made it more dangerous in the misguided attempt to make it safer.
It is an example of too much emphasis on egines, at the expense of weight/payload that would be available to spend on higher yielding safety features. (like fuel maybe)
AnFI - so far your total contribution to this thread (as in so many others) is to get poeple's backs up and make random statements to try and enforce your rather random opinion whilst trying to use pseudo-science to give validity to your viewpoints.
You will only be happy when everyone is flying around in single-engine aircraft happily ignoring the constant exposure because, according to your statistical analysis, engine failures don't count as a risk because they happen so infrequently.
If the great and good (and far more technically knowledgable) of the aviation world shared your views then we wouldn't have multi-engined aircraft................but they don't!
Now be a good troll and bother someone else since you clearly don't have anything of value to add.
You will only be happy when everyone is flying around in single-engine aircraft happily ignoring the constant exposure because, according to your statistical analysis, engine failures don't count as a risk because they happen so infrequently.
If the great and good (and far more technically knowledgable) of the aviation world shared your views then we wouldn't have multi-engined aircraft................but they don't!
Now be a good troll and bother someone else since you clearly don't have anything of value to add.
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Crab I cannot tell if you are making a technical point.
Are you in favour of exposure or not?
So far I understand that you don't like statistics, you disagree with me (on what specific point we don't know), and instead of actually making a point you'd like to be rude to me. If you carry on being rude to me then I am sure that I'll be banned for it, you have been warned.
You seem to be (deliberately?) misconstruing what I am saying also:
"according to your statistical analysis, engine failures don't count as a risk because they happen so infrequently."
That isn't even nearly what I said. ( the simple version of what I said is if you eliminate a small risk at the expense of creating a larger one then you have not reduced the risk but increased it)
Do you have anything to contribute beyond your attacks on me?
Are you in favour of exposure or not?
So far I understand that you don't like statistics, you disagree with me (on what specific point we don't know), and instead of actually making a point you'd like to be rude to me. If you carry on being rude to me then I am sure that I'll be banned for it, you have been warned.
You seem to be (deliberately?) misconstruing what I am saying also:
"according to your statistical analysis, engine failures don't count as a risk because they happen so infrequently."
That isn't even nearly what I said. ( the simple version of what I said is if you eliminate a small risk at the expense of creating a larger one then you have not reduced the risk but increased it)
Do you have anything to contribute beyond your attacks on me?
AnFI - I don't think anyone deliberately misconstrues what you say - it is just that you are not very good at putting your point (which apart from single engine is better than twin we don't really know) across.
Which exposure do you mean? Flying across the sea on one engine, temporarily entering the H-V curve in a twin, ditching a 737???
I know I flew defensively in a single and had to constantly consider the OEI performance in a twin in the low speed environment and there were some situations where an engine failure would have been very unpleasant whether in a single or a twin - but that was all in military ops where the risk/ reward balance is different.
if you can remove some risk relatively easily then you should do it - therefore flying pax in a SE helo is always going to be more risky (in terms of outcome following a single engine failure) than it will be in a twin.
As ever, you love to tease and play games with what your experience is or isn't - it's rather tiresome and you have no credibility on this forum when you do so - don't be surprised if people are rude to you.
Which exposure do you mean? Flying across the sea on one engine, temporarily entering the H-V curve in a twin, ditching a 737???
I know I flew defensively in a single and had to constantly consider the OEI performance in a twin in the low speed environment and there were some situations where an engine failure would have been very unpleasant whether in a single or a twin - but that was all in military ops where the risk/ reward balance is different.
if you can remove some risk relatively easily then you should do it - therefore flying pax in a SE helo is always going to be more risky (in terms of outcome following a single engine failure) than it will be in a twin.
As ever, you love to tease and play games with what your experience is or isn't - it's rather tiresome and you have no credibility on this forum when you do so - don't be surprised if people are rude to you.
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Crab "Which exposure do you mean? Flying across the sea on one engine, temporarily entering the H-V curve in a twin, ditching a 737???"
We are talking about "temporarily entering the H-V curve in a twin", I guess you actually agree with me but find that difficult?
Did you ever ditch?
Did you ever have any engine failure? (how did that work out for you?)
We are talking about "temporarily entering the H-V curve in a twin", I guess you actually agree with me but find that difficult?
Did you ever ditch?
Did you ever have any engine failure? (how did that work out for you?)
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AnFi:
I am trying to keep it on track.
JimL, Nick Lappos and I beleive that Exposure (in the sense above, being discussed) makes sense.
Mr WIz, Mr Paggi do not agree.
It is not clear where Crab stands on this issue.
I have given a pretty clear example of how this type of exposure can be safer
HT I am guessing that you are in the HOGEFAP camp?
We are talking about "temporarily entering the H-V curve in a twin", I guess you actually agree with me but find that difficult?
JimL, Nick Lappos and I beleive that Exposure (in the sense above, being discussed) makes sense.
Mr WIz, Mr Paggi do not agree.
It is not clear where Crab stands on this issue.
I have given a pretty clear example of how this type of exposure can be safer
HT I am guessing that you are in the HOGEFAP camp?
We are talking about "temporarily entering the H-V curve in a twin", I guess you actually agree with me but find that difficult?
This discussion is about poor legislation and certification vs the need to get the job done but the overriding argument has to be about safety.
As has been asked before - would you travel or put your wife and kids on an aircraft if you knew that an engine failure at a critical stage of flight would result in a hazardous visit to the scenery? Or would you rather that the certification and operating procedures ensured a safe landing or safe continued flight with no period (however short) of extra risk?
At TDP on an aircraft that needs penetration into the H-V curve, you are working the engines at MTOP - and if one is going to fail, that is the most likely time.
Yes I have had an engine failure in a twin but not at a critical stage of flight so no drama - would have been much more exciting in a single though.
This is getting quite amusing as a bystander here , but to put some sanity into the HV argument who can answer the following probability questions from actual information
1. chances of any engine failing at any point in the flight regime
2. chances of engine failing within HV curve
3. chances of a mechanical failure at any point
4. chances of mechanical failure within HV curve
5. chances of pilot error within any point of flight regime
6. chances of pilot error within HV curve
Once we know this information a sensible risk assessment can be made so ANFi can argue his point with actual information
Yes there is a risk to everything we do but ......
Before I get shot down too much I have had an engine failure at 100 ft 30 kts coming into land. Have had miss running engines requiring a landing 3 times in 7500 hours
I have taught my daughter to fly and yes into the H/v curve you have to to get a PPL. Flown my wife in and out of the H/V curve in both singles and twins, as i believe the risk of engine quitting is remote.
Yes you can argue what you want that a twin is better than a single but you could also argue what happens if the combining gearbox decides to take a break ??? Could have 3 engines doesn't make any difference. Again what is the probability of that.
It is all about weighing up risk and everyone has a different view. I would suggest that the pilot is the biggest risk not the machine.
Incoming
1. chances of any engine failing at any point in the flight regime
2. chances of engine failing within HV curve
3. chances of a mechanical failure at any point
4. chances of mechanical failure within HV curve
5. chances of pilot error within any point of flight regime
6. chances of pilot error within HV curve
Once we know this information a sensible risk assessment can be made so ANFi can argue his point with actual information
Yes there is a risk to everything we do but ......
Before I get shot down too much I have had an engine failure at 100 ft 30 kts coming into land. Have had miss running engines requiring a landing 3 times in 7500 hours
I have taught my daughter to fly and yes into the H/v curve you have to to get a PPL. Flown my wife in and out of the H/V curve in both singles and twins, as i believe the risk of engine quitting is remote.
Yes you can argue what you want that a twin is better than a single but you could also argue what happens if the combining gearbox decides to take a break ??? Could have 3 engines doesn't make any difference. Again what is the probability of that.
It is all about weighing up risk and everyone has a different view. I would suggest that the pilot is the biggest risk not the machine.
Incoming
Since my views with respect to 'Exposure' have been referred to, it is probably best that they be accurately expressed. Rather than provide a lengthy monologue, anyone who is interested in them can read them in soon to be published RAeS Discussion Paper shown in draft here:
https://www.dropbox.com/s/vq36s43on3...ed%29.pdf?dl=0
The link to the RAeS paper will be provided when it is published.
Two other issues that need clarification are:
Contrary to what has been stated, an engine failure within the Category B profile does require a landing within the serviceability limits of the helicopter in the take-off and landing profiles.
The scope of the H/V diagram was explained earlier in the thread in post 29 and was:
Jim
https://www.dropbox.com/s/vq36s43on3...ed%29.pdf?dl=0
The link to the RAeS paper will be provided when it is published.
Two other issues that need clarification are:
Contrary to what has been stated, an engine failure within the Category B profile does require a landing within the serviceability limits of the helicopter in the take-off and landing profiles.
The scope of the H/V diagram was explained earlier in the thread in post 29 and was:
The Conditions of an H-V Diagram
The H-V Diagram defines an envelope of airspeed and height above the ground from which a safe power-off or OEI landing cannot be made. The flight manual should list any procedures which may apply to specific points (e.g. high speed points) and test conditions, such as runways surface etc.
The surface condition has relevance to the H-V Diagram only inasmuch as it represents a further limiting condition – i.e. a landing is not guaranteed in the case of an engine failure outside the H-V avoid curve if the surface conditions do not permit it. In ICAO, this additional factor is included in the definition of a safe-forced-landing – which consists of two elements:
The H-V Diagram defines an envelope of airspeed and height above the ground from which a safe power-off or OEI landing cannot be made. The flight manual should list any procedures which may apply to specific points (e.g. high speed points) and test conditions, such as runways surface etc.
The surface condition has relevance to the H-V Diagram only inasmuch as it represents a further limiting condition – i.e. a landing is not guaranteed in the case of an engine failure outside the H-V avoid curve if the surface conditions do not permit it. In ICAO, this additional factor is included in the definition of a safe-forced-landing – which consists of two elements:
the rate of closure with the surface following an engine failure; and,
the conditions of the surface on which a touchdown is made
Only the former is a condition of the H-V Diagram. Surface conditions are non-sequitur and have no place in the determination of compliance.
the conditions of the surface on which a touchdown is made
Thanks for that link Jim - I think every pilot should be made to read that document.
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JimL:
Thank you so much for that, it's exactly what this debate needs, a framework for constructive discussion.
Crab:
I am grateful to you for answering the point.
And hopefully this answer to your questions will help you look at it in a different way(?):
Q1 "would you travel or put your wife and kids on an aircraft if you knew that an engine failure at a critical stage of flight would result in a hazardous visit to the scenery?"
Yes definately, and most certainly if the overall flight risk were less (obviously?).
Eg:
I would put them in a PC12.
I would not let them get in the 1970's Barron (which is mandated for PT, due to the type of logic you have used)
Q2: "Or would you rather that the certification and operating procedures ensured a safe landing or safe continued flight with no period (however short) of extra risk?"
No I would not like them to be subject, without a choice, to the increased risk associated with this approach. 2 Pilots, trained to a tickbox level, checked according to the CAA required level of competance, bored and ignorant, flying a 'look how bug my chopper is' ego trip machine. So no, the certification process, provides no confidence, hampers talented designers, creates absurd committee designed aircraft, with ludicrous gearboxes, fuel systems that even talented ex military pilots can't operate (apparently). So YES I'd be happy for them to be exposed to (the miniscule) engine risk in exchange for not having to suffer the additional risks disproportionately encountered in the (misguided) attempt to eliminate that obscure emotional risk.
I am yet to read all of JimLs paper but the probability analysis is at least a sound way to look at it. We just have to convince crab that a little probability theory is not as evil as he thinks, we are out of the dark ages aren't we?
There is a REALLY great way to look at risk. It is called the MICROMORT.
It is a unit of exposure to risk of 1:10^6 (ie 10^-6) of death.
It helps put in context the risks one takes and to get things into a rational perspective.
1 micromort is encountered when travelling by car 200 miles, motorbike 6 miles.
Being exposed to 9 seconds of 'exposure' adds about 0.02 of a micromort, whereas in the UK we face 0.8 micromorts per normal day (for non-natural death).
We do need protection from the logic that disregards science and fills people's heads with superstition. "Just imagine how terrible it would be if the engine quit just at this or that special moment, we must do something about it, we have a duty of care"
And if this (slightly mean spirited) mechanism were used then we could get it in perspective also:
"Value of a Statistical Life (VSL) - or Value for Preventing a Fatality (VPF) - to evaluate the cost-effectiveness of expenditure on safeguards."
A reduction in risk from one (already a very very low proportion of accidents) cause cannot justify increased risks in the other areas that are a much higher proportion of the accident causes.
(Crab, just curiousity, but for your one engine failure, what exact phase of flight were you in, cruise... over a rough sea at night? or a calm sea of about 10deg C in daytime? It's likely to have been the legendary 'dark and stormy night' in your old line of work i imagine)
Thank you so much for that, it's exactly what this debate needs, a framework for constructive discussion.
Crab:
I am grateful to you for answering the point.
And hopefully this answer to your questions will help you look at it in a different way(?):
Q1 "would you travel or put your wife and kids on an aircraft if you knew that an engine failure at a critical stage of flight would result in a hazardous visit to the scenery?"
Yes definately, and most certainly if the overall flight risk were less (obviously?).
Eg:
I would put them in a PC12.
I would not let them get in the 1970's Barron (which is mandated for PT, due to the type of logic you have used)
Q2: "Or would you rather that the certification and operating procedures ensured a safe landing or safe continued flight with no period (however short) of extra risk?"
No I would not like them to be subject, without a choice, to the increased risk associated with this approach. 2 Pilots, trained to a tickbox level, checked according to the CAA required level of competance, bored and ignorant, flying a 'look how bug my chopper is' ego trip machine. So no, the certification process, provides no confidence, hampers talented designers, creates absurd committee designed aircraft, with ludicrous gearboxes, fuel systems that even talented ex military pilots can't operate (apparently). So YES I'd be happy for them to be exposed to (the miniscule) engine risk in exchange for not having to suffer the additional risks disproportionately encountered in the (misguided) attempt to eliminate that obscure emotional risk.
I am yet to read all of JimLs paper but the probability analysis is at least a sound way to look at it. We just have to convince crab that a little probability theory is not as evil as he thinks, we are out of the dark ages aren't we?
There is a REALLY great way to look at risk. It is called the MICROMORT.
It is a unit of exposure to risk of 1:10^6 (ie 10^-6) of death.
It helps put in context the risks one takes and to get things into a rational perspective.
1 micromort is encountered when travelling by car 200 miles, motorbike 6 miles.
Being exposed to 9 seconds of 'exposure' adds about 0.02 of a micromort, whereas in the UK we face 0.8 micromorts per normal day (for non-natural death).
We do need protection from the logic that disregards science and fills people's heads with superstition. "Just imagine how terrible it would be if the engine quit just at this or that special moment, we must do something about it, we have a duty of care"
And if this (slightly mean spirited) mechanism were used then we could get it in perspective also:
"Value of a Statistical Life (VSL) - or Value for Preventing a Fatality (VPF) - to evaluate the cost-effectiveness of expenditure on safeguards."
A reduction in risk from one (already a very very low proportion of accidents) cause cannot justify increased risks in the other areas that are a much higher proportion of the accident causes.
(Crab, just curiousity, but for your one engine failure, what exact phase of flight were you in, cruise... over a rough sea at night? or a calm sea of about 10deg C in daytime? It's likely to have been the legendary 'dark and stormy night' in your old line of work i imagine)
Micromorts - FFS - more utterly pointless statistical analysis but I guess it is the sort of thing bean-counters love to bits.
if this is the opinion you have of your fellow professionals in the aviation business, maybe you should look elsewhere for employment.
My engine failure - which isn't relevant since it was in a military aircraft not subject to any civil performance criteria and not flying CAT - was a 100' crossing the airfield at RAF Valley for dispersal with a student in the RHS. No dramas and a safe running landing to the nearest taxiway.
Back to the wife and kids - if you put them as fare-paying pax into an aircraft that then crashed because additional exposure was experienced and the engine failed at a critical point - would you sue?
2 Pilots, trained to a tickbox level, checked according to the CAA required level of competance, bored and ignorant, flying a 'look how bug my chopper is' ego trip machine. So no, the certification process, provides no confidence, hampers talented designers, creates absurd committee designed aircraft, with ludicrous gearboxes, fuel systems that even talented ex military pilots can't operate (apparently).
My engine failure - which isn't relevant since it was in a military aircraft not subject to any civil performance criteria and not flying CAT - was a 100' crossing the airfield at RAF Valley for dispersal with a student in the RHS. No dramas and a safe running landing to the nearest taxiway.
Back to the wife and kids - if you put them as fare-paying pax into an aircraft that then crashed because additional exposure was experienced and the engine failed at a critical point - would you sue?