Where does the UK/JAR "twin only" mentality come from?
Avoid imitations
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The fact that I don't want to give identifying information does not infer, imply nor indicate anything at all about by twin flying credentials.
Your logic is faulty. Perhaps that is related to your illogical belief in duplicating engines (of all things)
Your logic is faulty. Perhaps that is related to your illogical belief in duplicating engines (of all things)
It's ridiculous to expect anyone on a professional forum to believe that illogical excuse. This constant "thing" against twin engined aircraft is both flawed and vacuous and is beginning to sound like a cracked record.
Your logic is faulty in more than one way. The reason twin engined aircraft appear in certain role accident statistics is because single engined aircraft are not allowed to carry out those roles. E.g. Night, or IFR, or offshore public transport.
Also, anyone old enough to have operated exclusively the old piston engined types you refer to would now be too old to still be flying commercially as a single pilot.
FYI, For some jobs (not all) I'd happily take an appropriately equipped, powerful modern single over a poorly equipped, older twin, including into IMC. I have experience of doing so, which I doubt you have, at least not legally. Now, see if you can, by your own logic, identify who I am.
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AnFI. You said:
I am prepared to be convinced. Though as yet I'm not. Can you please point me in the direction of ANY relevant data to support your case that singles are 'safer' than twins?
Very many thanks.
TR
and to simplifiy the discussion: the impact of a gearbox failure (more probable in a twin) in a twin is pretty dramatic too!! That's why it wrong to only look at the downside of the engine failure without accounting for the consequential other risks. Yes there should be less forced landings in twins due to engines, but more for other reasons, making them overall unjustified (in general).
Very many thanks.
TR
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Tand
I'm curious, Can you please point me in the direction of ANY relevant data to support your case that twins are 'safer' than singles?
Can you please point me in the direction of ANY relevant data to support your case that singles are 'safer' than twins?
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please take your incessant single lobbying to the regulators of the World. They make the rules. We don't.
The USA doesn't.
Singles are quite welcome here.
How about Record Setting Flights?
Great Circle Distance Without Landing
International: 2,213.04 mi; 3,561.55 km.
Robert G. Ferry (U.S.) in Hughes YOH-6A helicopter powered by Allison T-63-A-5 engine; from Culver City, Calif., to Ormond Beach, Fla., April 6–7, 1966.
Distance, Closed Circuit Without Landing
International: 1,739.96 mi; 2,800.20 km.
Jack Schweibold (U.S.) in Hughes YOH-6A helicopter powered by Allison T-63-A-5 engine; Edwards Air Force Base, Calif., March 26, 1966.
Altitude without Payload
International: 40,820 ft; 12,442 m.
Jean Boulet (France) in Alouette SA 315-001 Lama powered by Artouste IIIB 735 KW engine; Istres, France, June 21, 1972.
Speed around the World, Eastbound
40.99 mph; 65.97 kph.
Joe Ronald Bower (U.S.) pilot, in Bell JetRanger III, powered by one Allison 250-C20J (317 shp), covered 23,800 mi in 24 days, 4 hr., 36 min. June 28–July 22, 1994.
Speed around the World, Westbound
57.01 mph; 91.75 kph.
Joe Ronald Bower (U.S.) pilot, John W. Williams (U.S.), co-pilot in Bell 430 powered by 2 Allison 250–C40, (811 shp), Aug. 17–Sept. 3, 1996.
International: 2,213.04 mi; 3,561.55 km.
Robert G. Ferry (U.S.) in Hughes YOH-6A helicopter powered by Allison T-63-A-5 engine; from Culver City, Calif., to Ormond Beach, Fla., April 6–7, 1966.
Distance, Closed Circuit Without Landing
International: 1,739.96 mi; 2,800.20 km.
Jack Schweibold (U.S.) in Hughes YOH-6A helicopter powered by Allison T-63-A-5 engine; Edwards Air Force Base, Calif., March 26, 1966.
Altitude without Payload
International: 40,820 ft; 12,442 m.
Jean Boulet (France) in Alouette SA 315-001 Lama powered by Artouste IIIB 735 KW engine; Istres, France, June 21, 1972.
Speed around the World, Eastbound
40.99 mph; 65.97 kph.
Joe Ronald Bower (U.S.) pilot, in Bell JetRanger III, powered by one Allison 250-C20J (317 shp), covered 23,800 mi in 24 days, 4 hr., 36 min. June 28–July 22, 1994.
Speed around the World, Westbound
57.01 mph; 91.75 kph.
Joe Ronald Bower (U.S.) pilot, John W. Williams (U.S.), co-pilot in Bell 430 powered by 2 Allison 250–C40, (811 shp), Aug. 17–Sept. 3, 1996.
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MEH and SEHs each have their own applications that are best suited to either one or two engines based on risk and operational financial compromises.
However, to simplify the argument:
Operating over a hostile environment (an environment where no safe forced landing area exists - defined as an area where there is an expectation of damage or injuries to the occupants or persons on the ground); clearly a MEH with "stay up" performance is inherently more safe than a SEH.
That is the bottom line!
Any other discussion on this matter is just hot air and guff!
DB
However, to simplify the argument:
Operating over a hostile environment (an environment where no safe forced landing area exists - defined as an area where there is an expectation of damage or injuries to the occupants or persons on the ground); clearly a MEH with "stay up" performance is inherently more safe than a SEH.
That is the bottom line!
Any other discussion on this matter is just hot air and guff!
DB
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Chopjock
I have already said. I am prepared to be convinced if anyone can produce well researched data. However so far nobody has, and I am not! So it comes down to matters of opinion.
My opinion is based on a lifetime of being a professional pilot. I am an ATPL both fixed and rotary. Singles and multis. I am still earning my living as a full time pilot. Your opinion is based on flying radio control helicopters, and being a PPL(H). AnFI won't consider sharing his experience, incase he may be 'identified'??
So. Matters of opinion. I am very content that I seem to be in agreement with the overwhelming majority of professionals who post here. People who have both seen it, and done it!
I'm curious, Can you please point me in the direction of ANY relevant data to support your case that twins are 'safer' than singles?
My opinion is based on a lifetime of being a professional pilot. I am an ATPL both fixed and rotary. Singles and multis. I am still earning my living as a full time pilot. Your opinion is based on flying radio control helicopters, and being a PPL(H). AnFI won't consider sharing his experience, incase he may be 'identified'??
So. Matters of opinion. I am very content that I seem to be in agreement with the overwhelming majority of professionals who post here. People who have both seen it, and done it!
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So it comes down to matters of opinion.
My opinion is based on a lifetime of being a professional pilot. I am an ATPL both fixed and rotary. Singles and multis.
If there is no hard data to support twins are safer than singles
To avoid the deja vu that has affected recent discussions, it might be worth going back and reading the first three pages of this thread.
The posting by Mars in #44 appears to provide some data (first posted by SASless) on why twins are used offshore over a hostile environment.
Just to correct the basis of the statistics: the figure for engine failures (power plant, not core failures) comes out consistently at 1:100,000/flying hour. The probability of failure of an engine in a single is therefore 1 x 10**-5; the probability of an engine failure in a twin (one or the other) is 2 x 10**-5; and the probability of two failures in a twin (from unconnected causes - i.e. one and then the other) is 2 x 10**-5 and (times) 1 x 10**-5 - that is 2 x 10**-10. The consequences of a failure in twin should be negligible providing other elements of the operational code of performance (the performance classes) in Europe are applied as written.
With respect to the requirement for certification in Category A for flights over a hostile environment; it is more to do with the additional protection that is afforded to these helicopters in the design and build processes.
In none of the cases above is the helicopter protected from the vagaries of human factors (as is observed in the offshore statistics - both in the GOM and the North Sea). In this respect, AnFI is quite correct that the complexity of modern helicopters brings with it additional burdens for the operator and the crew members in terms of the requirement to understand complexity, and training to ensure competence it its use.
Jim
The posting by Mars in #44 appears to provide some data (first posted by SASless) on why twins are used offshore over a hostile environment.
Just to correct the basis of the statistics: the figure for engine failures (power plant, not core failures) comes out consistently at 1:100,000/flying hour. The probability of failure of an engine in a single is therefore 1 x 10**-5; the probability of an engine failure in a twin (one or the other) is 2 x 10**-5; and the probability of two failures in a twin (from unconnected causes - i.e. one and then the other) is 2 x 10**-5 and (times) 1 x 10**-5 - that is 2 x 10**-10. The consequences of a failure in twin should be negligible providing other elements of the operational code of performance (the performance classes) in Europe are applied as written.
With respect to the requirement for certification in Category A for flights over a hostile environment; it is more to do with the additional protection that is afforded to these helicopters in the design and build processes.
In none of the cases above is the helicopter protected from the vagaries of human factors (as is observed in the offshore statistics - both in the GOM and the North Sea). In this respect, AnFI is quite correct that the complexity of modern helicopters brings with it additional burdens for the operator and the crew members in terms of the requirement to understand complexity, and training to ensure competence it its use.
Jim
Boudreaux Bob,
Of course the US know better, everyone knows that....
Only last week I was looking at a Yank video of a 500D doing an EOL over a built up area because of a problem with his (one and only) engine (the mayday thread). Over the years I have read of several 'incidents' where yanks have force landed in built up areas due to the lack of duplication.[And I am NOT talking about ancilliaries like gearbox, combiner boxes, tail rotor etc].
All your "examples" are Private flights - and these aren't the worry when it comes to losing an ECU. If a private individual wants to risk these things on one engine - who cares?
Public transport is much more sensitive to issues regarding duplication and I would suggest (both through anecdotal and personal evidence) that twins are safer in this domain and for protecting joe public. In fact I cannot think of any UK incident where a twin has come down over a built up area due to total engine(s) failure other than Strathclyde and this is allegedly fuel related.
Of course the US know better, everyone knows that....
Only last week I was looking at a Yank video of a 500D doing an EOL over a built up area because of a problem with his (one and only) engine (the mayday thread). Over the years I have read of several 'incidents' where yanks have force landed in built up areas due to the lack of duplication.[And I am NOT talking about ancilliaries like gearbox, combiner boxes, tail rotor etc].
All your "examples" are Private flights - and these aren't the worry when it comes to losing an ECU. If a private individual wants to risk these things on one engine - who cares?
Public transport is much more sensitive to issues regarding duplication and I would suggest (both through anecdotal and personal evidence) that twins are safer in this domain and for protecting joe public. In fact I cannot think of any UK incident where a twin has come down over a built up area due to total engine(s) failure other than Strathclyde and this is allegedly fuel related.
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Police Ops in the USA are not Public Transport.
The FAA classifies them as "Public Use" and do not regulate those Operations.
Part 135 which covers "Air Taxi Operations" also does not require Twin Engined Helicopters.
The UK attitude, be it formed by the CAA or other political interests, is unique to the UK and now EASA I guess.
The question is whether that attitude is founded upon Science or mere Whim.
I seem to recall a couple of Twins landing in downtown London and in Glasgow that killed people on the ground.
Explain that away to me will you?
How does a second engine in both those crashes figure into the death and injuries that were caused?
You guys over there are way too much into the Nanny State Mentality!
The FAA classifies them as "Public Use" and do not regulate those Operations.
Part 135 which covers "Air Taxi Operations" also does not require Twin Engined Helicopters.
The UK attitude, be it formed by the CAA or other political interests, is unique to the UK and now EASA I guess.
The question is whether that attitude is founded upon Science or mere Whim.
I seem to recall a couple of Twins landing in downtown London and in Glasgow that killed people on the ground.
Explain that away to me will you?
How does a second engine in both those crashes figure into the death and injuries that were caused?
You guys over there are way too much into the Nanny State Mentality!
Purveyor of Egg Liqueur to Lucifer
Excuse me Bob, you haven't answered the question as to why the New York City Police only have twins.
Type into google, New York helicopter crash and you'll find many singles .... and only one twin, the police helicopter.
Type into google, New York helicopter crash and you'll find many singles .... and only one twin, the police helicopter.
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As an outsider, i'd like to offer the following.....
Single engine.....fire goes out, you're going down.
2 engines....TWICE the probability of engine (or extra transmission components, V a single) failure BUT at least you have one Donk, albeit it's lugging the weight and drag of the dead 'un, to give you a bit of flight TIME in which to find a landing-site.
I see no relevance in the reliability issue, provided we're comparing an apple with 2 apples......it's a different and pointless exercise to compare 2 apples with one orange.
Twin adds a margin of extra safety, but at a horrendous financial premium.
Single is a fraction of the FINANCIAL cost, but what value lives, families and pilots.
Nanny state makes that decision for us.
Perhaps the penalty of wide-spaced landing-gear, with rigid, streamlined floats, could be an option for single-engine over-water ops?
Of course, even then, sea-state would have a big effect on outcome....but twins still ditch and people still die......
Single engine.....fire goes out, you're going down.
2 engines....TWICE the probability of engine (or extra transmission components, V a single) failure BUT at least you have one Donk, albeit it's lugging the weight and drag of the dead 'un, to give you a bit of flight TIME in which to find a landing-site.
I see no relevance in the reliability issue, provided we're comparing an apple with 2 apples......it's a different and pointless exercise to compare 2 apples with one orange.
Twin adds a margin of extra safety, but at a horrendous financial premium.
Single is a fraction of the FINANCIAL cost, but what value lives, families and pilots.
Nanny state makes that decision for us.
Perhaps the penalty of wide-spaced landing-gear, with rigid, streamlined floats, could be an option for single-engine over-water ops?
Of course, even then, sea-state would have a big effect on outcome....but twins still ditch and people still die......
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How in the Hell would I know Sid?
What does it matter?
They are but one Police Department.
LAPD has a fleet of Singles.
LASO has some Twins.
Miami-Dade has some.
But Twins are rare and most importantly ARE NOT REQUIRED BY OUR LAW.
So your turn Sid.
Why does the UK REQUIRE TWINS?
What does the CAA base that requirement upon?
What Scientific Empirical Data did they use when they issued that Edict?
The Thread is about the UK/JAR "Twin Only" Mentality as you recall.
Stick to the Topic of the Thread.
What does it matter?
They are but one Police Department.
LAPD has a fleet of Singles.
LASO has some Twins.
Miami-Dade has some.
But Twins are rare and most importantly ARE NOT REQUIRED BY OUR LAW.
So your turn Sid.
Why does the UK REQUIRE TWINS?
What does the CAA base that requirement upon?
What Scientific Empirical Data did they use when they issued that Edict?
The Thread is about the UK/JAR "Twin Only" Mentality as you recall.
Stick to the Topic of the Thread.
Purveyor of Egg Liqueur to Lucifer
Bob,
I think it marvellously funny when you tell us;
When the first location you mention doesn't actually have any singles.
I just love your answer to the question, 'Why do the New York Police only operate twins';
It matters Bob, because you seem to know why singles are so much better than twins, you are arguing that twins in police operations aren't necessary etc ... however your own New York Police Department seems to disagree with everything you say. Perhaps you'd better pay them a visit and tell them where they are going wrong 
I think it marvellously funny when you tell us;
New York City clear across to Los Angeles my country is populated with dozens and dozens of Police Helicopter Operations and almost all use Single Engined Helicopters exclusively for Day and Night flying.
I just love your answer to the question, 'Why do the New York Police only operate twins';
How in the Hell would I know Sid?
What does it matter?
What does it matter?
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Sid,
I have not taken any position re Twins or Singles.
I informed you of the US FAA Regulations.
The Thread is about the UK Twin Mentality.
Stick to the Topic. Why does the UK insist upon Twins for Police Work?
You unable to answer that question?
If not, perhaps you should just listen and watch as others discuss the topic.
I have not taken any position re Twins or Singles.
I informed you of the US FAA Regulations.
The Thread is about the UK Twin Mentality.
Stick to the Topic. Why does the UK insist upon Twins for Police Work?
You unable to answer that question?
If not, perhaps you should just listen and watch as others discuss the topic.
Purveyor of Egg Liqueur to Lucifer
Instead of just sitting there with no position either way, spouting off about not being regulated, perhaps it would help us to understand why we have a UK twin mentality if you could try to explain that despite there being no regulation on the matter in the US, the NYPD only have twins.
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Sid,
I am not from the UK and certainly do not understand the way you folks think about helicopter aviation from what I have read here over the years.
The thing that really bugs me is when challenged by others from outside the UK, some of you climb astride a very tall Horse and raise your nostrils to the drizzle.
I simply injected information about the US FAA Rules and Regulations to show that not all Countries insist on Twin Engine Helicopters.
For the third time Sid, the thread is about the UK and its "Twin Mentality".
Do try to keep up will you?
I am not from the UK and certainly do not understand the way you folks think about helicopter aviation from what I have read here over the years.
The thing that really bugs me is when challenged by others from outside the UK, some of you climb astride a very tall Horse and raise your nostrils to the drizzle.
I simply injected information about the US FAA Rules and Regulations to show that not all Countries insist on Twin Engine Helicopters.
For the third time Sid, the thread is about the UK and its "Twin Mentality".
Do try to keep up will you?
Boudreaux Bob - oooh we have a feisty one here with you don't we. Where have you been all these years me old?
Here - go to bed early tonight and take this with you - you'll be asleep within minutes
Where does the UK/JAR "twin only" mentality come from? [Archive] - PPRuNe Forums
The main post being:
Here - go to bed early tonight and take this with you - you'll be asleep within minutes
Where does the UK/JAR "twin only" mentality come from? [Archive] - PPRuNe Forums
The main post being:
There is no twin-only mentality; the restriction on flights over a hostile environment (and specifically a congested hostile environment) arises from compliance with the ICAO Annexes - you know, the Chicago Convention to which all States agree to comply:
Specifically:
ICAO Annex 2 - Rules of the Air; and Annex 6 - Operation of Aircraft.
Respectively, the need to 'land clear' (protection of third parties) and the requirement for a 'safe-forced-landing' (protection of crew and passengers).
There is also linkage to the the certification principle that no hazardous outcome should be permitted with an event which has a classification of 'Reasonably Probable' (which is based upon a probability on the order of between 1:1,000 and 1:100,000). Because engines tend to fail within that probability spectrum, ICAO SARPs attempt to keep the helicopter away from an area where the effect of the failure could be hazardous.
Specifically:
ICAO Annex 2 - Rules of the Air; and Annex 6 - Operation of Aircraft.
Respectively, the need to 'land clear' (protection of third parties) and the requirement for a 'safe-forced-landing' (protection of crew and passengers).
There is also linkage to the the certification principle that no hazardous outcome should be permitted with an event which has a classification of 'Reasonably Probable' (which is based upon a probability on the order of between 1:1,000 and 1:100,000). Because engines tend to fail within that probability spectrum, ICAO SARPs attempt to keep the helicopter away from an area where the effect of the failure could be hazardous.