Twins vs Singles...for safety

[DynamicallyUnstable]

Ok, so something I read in a different thread caused me to engage. I started hijacking the thread and decided to start a new one to discuss this.

In another thread, this was written....

 

It's comforting knowing you can pick the place you're gonna land engine out, but twins are much more work than singles the rest of the time- systems management, planning, etc. It is nice planning for the 'uh-oh' by considering OEI climb and fuel burn instead of "what do I do to to keep a survivable landing place in range"...

 

 

Planning what? More fuel burn? Not that big of a deal. I would say in my experience that twins are actually less work most of the time as usually when you have a twin you also have tools to make your life easier like autopilots, dual hydraulics, etc.

 

 

Mebbe in the newer ones it's simpler, but 15 years ago it the extra work started before you sat in it- what mod config you were flying today, fuel systems especially, and electricals? (large fleets ain't all the same, aircraft to aircraft- yes, singles vary as well but singles have simpler systems to have been modded); figuring T/O weight is the same functionally, but calculating and documenting CG, fore and aft; performance planning (Vxse & Vyse, for instance); and just starting the pig takes longer. I'm a pilot to fly...Once started, more systems, more checks; Autopilots have to be checked, too; bring them both up to the flight gate, and it's a single again- if the torques or NG match. Of course it never happens to 'good' pilots: attempting to lift with one in ground idle, or shutting down the wrong engine are functions of and examples of system complexity...If your training and maintenance are adequate and your and customer situation allows you to operate it as a twin, then twins enjoy a safety margin. Given those, I'd take a twin anyday, but easier they ain't. Without those favorable factors, twins are LESS safe.

 

 

OP, you must run in a different class than I do. Cause all the twins I have been in didn't have A/Ps. They are too heavy. In utility work every ounce counts. As for the Hyd systems, just because you have two pumps doesn't mean they power the same items or all of them. In the 212, sys 1 powers all the flight controls, but sys 2 only powers the main rotor. So if you have a sys 1 failure, your workload increases. Statistically twins are not any safer than single engine helicopters, partly because the engines and fuel systems are so closely connected, but also for some of the things we do with helicopters.

 

 

That just might be the craziest thing I have read on this forum. No offense but if I were flying over mountainous terrain at night and had my choice of losing an engine in an AS350 or losing an engine in an EC135...you get my point.

Yes there are more systems in the 135 than the 350 but they aren't there for anything other than safety. From the AP to the dual hydraulics (JD, you can chime in on that one haha) to the second engine...it's safer in every way that I can possibly think of.

As far as doing different things in AC that are twin vs. single, a LOT of those AC share jobs. From EMS in an EC135 or a B206 or slinging from a B205 to a B412.

You mentioned losing a hydraulic system in a 212 making the workload more... can you imagine it only having 1 hydraulic system and being uncontrollable? Lose a hydraulic system in an EC130...not a bit of difference in flyability!

 

Of course if there is something I'm missing here, I'm open to discuss.

[DynamicallyUnstable]

Oh and as far as higher workload...

 

I would take an EC135 over an AS350 for just about anything (with the exception of a B3 for altitude). Doing a SPIFR ILS in an EC135, cake...in an Astar???? Nope

[Wally]

There are a whole host of factors to be considered in the question.

Twins cost more, why would an operator buy one? To improve safety in high risk situations. That's a big, big clue- the operator intends to use the helo in places where they judge single engine ops too risky. Example- when I was flying TwinStars in the Gulf of Mexico, I was expected to use cross country minimums of 300 and 2 while singles were 'limited' to 500 and 3. Same nav equipment, often the same pilots. Ahh, but I had redundant power sources in my twin, right? Usually too heavy to fly OEI, or too far out to get to the beach. And the greatest hazard in that situation is the weather...

How about mountains? I like twins when the terrain sucks for power failures. See above- situations exist where you can't fly out of the hole or get anywhere if you did. Add that if the hazard exists (stuck OEI), you need to plan to avoid it (extra work and opportunity for error) and there will still be times you're faced with crashing a flyable helicopter to survive... How many times has get home-itis been an accident factor? You think it's different for twin drivers?

IFR, single/twin is less of a factor for a credible operator. If you work for a shoe-string type that wants IFR and opts for twin to make that happen- you're on your own, pard, and that factor has to be seen as a negative, too.

So twins are desirable as an operators means of offsetting increased risk = riskier situations, less safe.

 

The nature of the beast works against you because twins ARE more complicated. A quoted post mentions autopilots, not always included in multis but common in IFR, commonly multi-engine. An excellent example of the value of training in complex systems- autopilots will kill you if you're not well trained and don't operate them carefully. Has happened and will again.

Dual hydraulics- I can cite examples where single hydraulic systems mismanaged have killed people. Systems that power this but not that, in some configurations invite mistakes.

Electrical systems: Know what a main bus is? Which generator powers which bus? Which items are on which bus? Which mod are you in? Examples of twin complexity, and complexity kills when the chips are stacked against you.

Fuel: I like having separate fuel systems and crossfeeds. You can be out of fuel with lots on board. Yes, I know about Long Rangers, too...

The cliche is that "you have already, or you will..." applies to pulling the wrong engine off-line, or attempting a takeoff single engine in a twin. Much less an issue in singles. Not to mention matching engine parameters invites distraction, and distraction is an increased risk factor.

Doing all the planning required IS a risk multiplier and managing the systems are risk multipliers. If you're in a launch quickly and at unpredictable times situation, self-imposed pressure makes for bad decisions.

Are you well trained in all this? Some training programs barely cover singles, what you don't know can kill you.

 

And the big killer in twins- Invulnerability: I have two engines, I don't have to worry about "X, Y, or Z". I have heard that too often to think it's exceptional. Fact is, you have two engines, you have to consider "X, Y or Z" in entirely different lights- an engine failure at a high hover sucks single engine. Me, I think it's much more hazardous to have one of two quit and then crash at speed because I'm trying to fly out of it...

 

There were statistics specific to the question posted annually on an Offshore Oil and Gas producers web site out of Europe somewhere. Twins and singles swapped back and forth over the years for accident rates. Twins aren't inherently 'safer'.

[Oil Pilot]

With a properly trained pilot, twins are absolutely safer than singles.

 

Wally and I, like many others before us, disagree on this facet of the helicopter world.

 

Honestly, I can understand the bad taste in your mouth if you flew Twinstars.

 

Lets ask this question. Given the option, would you rather have a hydraulics failure in a 212 or an EC-120?

[Gunner]

Bottom line is that it all comes down to decision making... Look at what is causing the most accidents in our industry. IIMC and CFIT.

That extra engine does not matter when you take off in to a thunderstorm or punch in to the clouds and are not ready for it....

[DynamicallyUnstable]

Ok, lots to break up here. I have some time so let's do it.

 

There are a whole host of factors to be considered in the question.

Twins cost more, why would an operator buy one? To improve safety in high risk situations. That's a big, big clue- the operator intends to use the helo in places where they judge single engine ops too risky. Example- when I was flying TwinStars in the Gulf of Mexico, I was expected to use cross country minimums of 300 and 2 while singles were 'limited' to 500 and 3. Same nav equipment, often the same pilots. Ahh, but I had redundant power sources in my twin, right? Usually too heavy to fly OEI, or too far out to get to the beach. And the greatest hazard in that situation is the weather...

 

 

As far as cost goes...I don't care one bit what the helicopter I am flying cost. Just like I don't care how much money my operator made last month with me flying it. Those numbers do not apply to me. I don't have to pay for the helicopter and I don't get a bonus when my operator makes a lot more than expected for the month. I care about flying the safest equipment in the safest situation I can. THAT'S IT

Our weather minimums are the same twin or single (VFR of course) and to have different weather minimums based solely on the basis of twin vs. single I don't agree with at all for reasons you stated. Able to continue flight OEI or not, I don't see how the twin would deserve lower weather minimums but hey, that's just me. Many of us know what they say about the Twinstar so like OP, I can see why you'd have a bad taste in your mouth but you can't classify twins in the same light because the TS is less than desirable in an OEI situation.

 

How about mountains? I like twins when the terrain sucks for power failures. See above- situations exist where you can't fly out of the hole or get anywhere if you did. Add that if the hazard exists (stuck OEI), you need to plan to avoid it (extra work and opportunity for error) and there will still be times you're faced with crashing a flyable helicopter to survive... How many times has get home-itis been an accident factor? You think it's different for twin drivers?

 

 

Yes, get-home-itis could play a role in the twin driver OEI, I could see that BUT if the same pilot were in a single, the option is not even there. Does that make it more safe that the aircraft decides when it is time to make an unpowered landing? No way. So that comes down to the pilots ADM, not the aircraft issues. If the pilot decides to continue flight OEI because of get-home-itis, well... like I said, it's their own fault if something further happens that makes it a more dangerous situation, at least they made the decision instead of the machine.

 

 

IFR, single/twin is less of a factor for a credible operator. If you work for a shoe-string type that wants IFR and opts for twin to make that happen- you're on your own, pard, and that factor has to be seen as a negative, too.

So twins are desirable as an operators means of offsetting increased risk = riskier situations, less safe.

 

When I was faced with working on a SPIFR program VS. a VFR program I thought about a few things. If you are in a capable aircraft with all the "bells and whistles" and you are a well trained capable pilot, wouldn't you argue that flying IFR is actually a LOT safer than flying near minimums VFR?? I know given the choice, I'll take the pop-up and KNOW that I am clear of terrain, obstacles, wires, etc. So we can't see outside...that's something we were trained for. It blows my mind to hear you refer to an operator that operates the top notch equipment as "shoe string" which seems to translate into the operator being less responsible then...well I don't know what to say.

 

The nature of the beast works against you because twins ARE more complicated. A quoted post mentions autopilots, not always included in multis but common in IFR, commonly multi-engine. An excellent example of the value of training in complex systems- autopilots will kill you if you're not well trained and don't operate them carefully. Has happened and will again.

 

 

I'm sure you're not blaming a lack of training or an incompetent pilot or whatever else caused an accident on an auto pilot, right? Sure an AP may not be a perfect system 100% of the time but a pilot that is monitoring instrumentation in IFR and knows what is going on and knows what the instruments should be showing should be without much issue if the AP were to malfunction, no?

 

 

 

Dual hydraulics- I can cite examples where single hydraulic systems mismanaged have killed people. Systems that power this but not that, in some configurations invite mistakes.

 

Ok, I can see that being an issue but like OP said above, what would you rather be in??

 

 

 

Electrical systems: Know what a main bus is? Which generator powers which bus? Which items are on which bus? Which mod are you in? Examples of twin complexity, and complexity kills when the chips are stacked against you.

 

Again, proper training and proficiency.

 

 

Fuel: I like having separate fuel systems and crossfeeds. You can be out of fuel with lots on board. Yes, I know about Long Rangers, too...

The cliche is that "you have already, or you will..." applies to pulling the wrong engine off-line, or attempting a takeoff single engine in a twin. Much less an issue in singles. Not to mention matching engine parameters invites distraction, and distraction is an increased risk factor.

 

Haha, true, you won't take off in a single without starting an engine and you could in a twin... It goes back to training, cross checks, company policy (having crew challenges, etc.) With proper precautions it's VERY unlikely and a "risk" worth having for the benefit of two engines IMO.

 

 

 

Doing all the planning required IS a risk multiplier and managing the systems are risk multipliers. If you're in a launch quickly and at unpredictable times situation, self-imposed pressure makes for bad decisions.

Are you well trained in all this? Some training programs barely cover singles, what you don't know can kill you.

 

"all the planning"? What planning are we talking about that is in such excess to flying a single for the same mission?

Inadequate training can kill you in ANY situation, twin or single...I don't see the relevance.

 

 

 

And the big killer in twins- Invulnerability: I have two engines, I don't have to worry about "X, Y, or Z". I have heard that too often to think it's exceptional. Fact is, you have two engines, you have to consider "X, Y or Z" in entirely different lights- an engine failure at a high hover sucks single engine. Me, I think it's much more hazardous to have one of two quit and then crash at speed because I'm trying to fly out of it...

 

 

The example you give of invulnerability is another ADM issue IMO, not "having another engine" issue. Seriously, you'd rather be hovering at 300' in a single than hovering at 300' in a twin and lose 1 engine?? I must be missing something.

 

 

 

There were statistics specific to the question posted annually on an Offshore Oil and Gas producers web site out of Europe somewhere. Twins and singles swapped back and forth over the years for accident rates. Twins aren't inherently 'safer'.

 

Still open for discussion

[iChris]

The following is from a paper written on the issue of safety by Roy Fox that addressed the myths around twins vs. singles:

 

 

 

 

THE HISTORY OF HELICOPTER SAFETY

Roy G. Fox Bell Helicopter Textron, Inc. Fort Worth, Texas

(Page 12 - 14)

There are several myths in helicopter safety that need to be understood and corrected. We must work with facts, and not perceptions that are not necessarily true. These perceptions prevent the industry from moving forward based on facts. Some continuing myths are "Twin-engine helicopters are always safer than single engine helicopters.

 

The rest of the aircraft other than the engines are the same on single or twin engine helicopters, so it can be disregarded, etc." These myths are not always true and draw attention away from the rest of the aircraft and the largest and far more complex problem of the human pilots.

 

Concentration on the myths further ignores the different hazard levels of different types of missions, which can have significant effects. Over the last 20 years, these myths and ramifications have been discussed in Refs. 2, 12, 13, and 17. There are situations where an occupant in a twin-engine helicopter is safer than in a single engine helicopter, but the reverse is also true.

 

Another myth is that all helicopters are created equal and their safety is equivalent. That is not true either. Every helicopter model is different and has good and less-desirable features and characteristics.

 

The author considers all helicopters to be safe, but some are safer than others. To illustrate this fallacy of these myths, see Fig. 11 from Ref. 17, which shows the occupant's flight life span, which is the average number of hours, an occupant can fly before receiving a fatal injury.

 

This is the reciprocal of the RFI or 1/RFI. The time period is 1987 to 1996 for U.S. registered helicopters. The red bars are the flight life span, if you could only die from all airworthiness failures (including engine). Of course, "All Causes" data are the real measure of concern, and even 85,000 hours is a long, long time for an individual to be in the air.

 

Ref link below:

 

THE HISTORY OF HELICOPTER SAFETY

 

Edited February 23, 2011 by iChris

[Wally]

The most common cause of accidents is pilot error. In fact the vast majority of accidents are pilot error. Twins are more complex than singles creating more opportunity for error to cause an accident.

 

Two pilots improve safety in any equipment type and two pilot IFR (almost always twins) is magnitudes better yet in the statistics I have seen. I suspect that if there were more two-pilot IFR in singles they would have comparable safety stats. Two pilots reduce the likelihood of pilot error and IFR controls the risk environment.

[DynamicallyUnstable]

 

The obvious problem with this study is the number of singles vs. twins actually flying AND since it is the history instead of a given time period, you have to look at how many twins have been added to the WORLD helicopter industry in the last 20+ years. The ratio in 1980 might have been 1:20 twins vs. singles flying and now it may be closer to 1:15 (just using numbers as a type example reference, not actual figures). That is also something to figure out. If a proper study is to be conducted, it needs to also include how many TOTAL flight hours the singles in the study have flown and how many flight hours the twins have flown...TOTAL....EVER.

 

Twins are more complex than singles creating more opportunity for error to cause an accident.

 

Yes Wally, I agree that the twins will usually have more systems which could I suppose lead to more pilot error but the pilot mistakes or malfunctions that they potentially make up for I think would sway the figures in the opposite direction. Show me an example of where higher complexity of aircraft caused the error that resulted in a crash and that the error would not have happened in a less complex machine and I'll bet I could show you 100 times where the complexity of the aircraft helped to prevent an accident! Anytime there has been a hydraulic failure of a machine that only had a single hydraulic system and crashed...anytime that a single engine quit over mountainous terrain day or night and resulted in a crash...anytime a pilot was scud running because he didn't have the equipment to just go IFR and fly safely...etc.

It seems to me that your argument would say that a stripped out B206 or AS350 is safer than a loaded up EC135 or MD902 because it has FEWER systems. Fewer systems to malfunction means fewer things that can go wrong and fewer things that the pilot has to screw up. Right??? Man, I have GOT to be misunderstanding you. All the advances in technology have only brought us backwards then right? Come on man, you can't actually believe that. In this case, less is not more.

[iChris]

The obvious problem with this study is the number of singles vs. twins actually flying AND since it is the history instead of a given time period, you have to look at how many twins have been added to the WORLD helicopter industry in the last 20+ years. The ratio in 1980 might have been 1:20 twins vs. singles flying and now it may be closer to 1:15 (just using numbers as a type example reference, not actual figures). That is also something to figure out. If a proper study is to be conducted, it needs to also include how many TOTAL flight hours the singles in the study have flown and how many flight hours the twins have flown...TOTAL....EVER.

 

The paper covered from the 1940s through 2004. Figure #11 time period is 1987 to 1996 for U.S. registered helicopters. The red bars are the flight life span, if you could only die from all airworthiness failures (including engine).

 

In its conclusion helicopter safety has been improving over the years. The accident frequency appears to be flat or even increasing. The accident rates due to airworthiness issues (which include engine failure) remain very low and consistent year-to-year.

 

There are situations where an occupant in a twin-engine helicopter is safer than in a single engine helicopter, but the reverse is also true. What the paper points out is non-airworthiness issues account for far more fatal accidents. Some narrow their viewpoint to that one issue of the engine failing. History shows that may be the least to worry about and the pilot could be the weakest link in the chain.

 

The largest single potential area to make significant improvement in safety is in understanding what went on in the cockpit of each accident helicopter.

Edited February 24, 2011 by iChris

[Seo]

Hello Dear Collegues,

I would suggest you to be a little more open minded.

I'm flying every day aerial work long line in the swiss alps up to 9'000 ft with a single engined Lama.

I'm really "home" in the dead man curve of the Height/Velocity diagram. No twin engines can put the same performances in this wheight class, and if they exist, that would economical not affordable.

 

I'm also part time accident expert for the helicopter branch.

 

HEMS, Oil platform operations etc (may) have big money, or just enough to operate a twin Cadillac similar luxus helo, but my surrounding is working every day with cheaper singles.

 

I'm in this job since some 23 years and I can recall a single engine failure of T53-17 because of wrong RIN computing. My collegue died then.

 

I believe that we all fly some uneventful 20'000 hrs @ year while doing aerial work on singles and this just only in Switzerland.

Mechanical failure may be improved by a meticolous maintenance based on know how and experience.

Cougar twin S92 showed to you all that even twins may have catastrophic failures... how about it?

 

Your answer should then be:

put a second gearbox in!! Isn't?

 

No, that is the wrong approach.

 

Fail safe is the right one.

 

One month ago while flying at 6'000 ft with an external load of some 1900 lbs attached to a 60 ft line, my collegue saw that the T4 indicator was showing higher temperature than usual.

Usually the old Turbomeca Artouste IIIB-1 show in similar conditions not more than 450' Celsius; but suddendly the indicator was rising well about limitations!

 

He just posed the load on ground, descended than to the nearly airport, just close to the construction site, where we usually performs maintenance, declaring engine indication troubles to the tower.

He landed safe and shutted the engine off by the normal way.

Nothing happened, but from far away, a BIG (I mean VERY BIG!) crack was observable extending some 10 cm on the upper rear side of the combustion chamber about 1 cm wide!!!

 

In each case the engine suffered such thermal overload that the whole hot section is to be scrapped, but it was still running!

 

Who need a twin, when such singles are performing so redundant well and safe??

 

You see? It all depends on your point of view but please, please do not make the silly mistake to erect yourself at the top of your bench like professors who impose to legislators to adopt rules that have a negative impact on operators'needs which are different from yours.

We all need common sense!

 

External load peoples are not crazy, they are just living in another reality.

 

About rection time in event of an engine failure?

 

While hovering during aerial work at the maximal power setting, an engine fail would be just not recoverable, even with a twin which would need some less handling from the pilot.

More personally in similar conditions I fear a tail rotor than an engine failure.

 

So my dear collegues put some pressure to manufacturer to build up reliable and overpowered helicopters where engines are operating just close to the 85% of their thermal envelopment and let legislators in peace.

That would bring safe back in our operations.

 

I whish you all to become pilots to be withdrawn on ground for age reasons.

 

Stay safe, keep Health and.. eat Swiss Cheese.

 

Sergio

[Wally]

DynamicallyUnstable-

Yes, it IS counter intuitive that a more capable aircraft COULD be less safe. The conditional part of that statement- COULD be less safe, is where rational thought should happen- why might that be so? Well, it's because pilot error is the biggest cause of accidents, not power failures, power failures are what twins are about. They're an answer to a very isolated occurrence.

Here's a cliche question- Ever pulled the wrong engine off? Like all accidents: you have already, or you will, or you're invulnerable, which is a whole 'nother problem. It happens in singles (Yes, it does!) but that sorta reinforces my argument- complexity promotes error and pilot error is what causes between 75-90% of accidents. Pull the engine off in a single, and the remedy is simple if you got time- put it back. Do it in a twin and in the heat of the issue being addressed, it's possible that you won't even identify that mistake as a cause of your new problem- the impending crash. Implementing a remedy is supposed to make things better... Not everybody sorts that out. You have, or you will at some point, shut down the wrong system in a twin.

Simpler, when adequate, is always safer. Am I saying that simpler is always BETTER? Not at all, the advantages the convinced twin guys tout are very real. But, one needs to acknowledge that there's no free lunch- added complexity increases the possibility of error, and error is the primary cause of aviation accidents. The stats I'm most familiar with showed the numbers going back in forth, year to year, between light twins and singles in the same job. If I get time and remember, I'll dig up the source of the stats...

 

Don't confuse the issue with assumptions about twin IFR, autoplilots, etc., they come with their own challenges. Scud running is not a single engine or non-IFR issue, either. That's judgement issue, IFR capability doesn't make the PIC smarter.

 

 

 

The obvious problem with this study is the number of singles vs. twins actually flying AND since it is the history instead of a given time period, you have to look at how many twins have been added to the WORLD helicopter industry in the last 20+ years. The ratio in 1980 might have been 1:20 twins vs. singles flying and now it may be closer to 1:15 (just using numbers as a type example reference, not actual figures). That is also something to figure out. If a proper study is to be conducted, it needs to also include how many TOTAL flight hours the singles in the study have flown and how many flight hours the twins have flown...TOTAL....EVER.

 

 

 

Yes Wally, I agree that the twins will usually have more systems which could I suppose lead to more pilot error but the pilot mistakes or malfunctions that they potentially make up for I think would sway the figures in the opposite direction. Show me an example of where higher complexity of aircraft caused the error that resulted in a crash and that the error would not have happened in a less complex machine and I'll bet I could show you 100 times where the complexity of the aircraft helped to prevent an accident! Anytime there has been a hydraulic failure of a machine that only had a single hydraulic system and crashed...anytime that a single engine quit over mountainous terrain day or night and resulted in a crash...anytime a pilot was scud running because he didn't have the equipment to just go IFR and fly safely...etc.

It seems to me that your argument would say that a stripped out B206 or AS350 is safer than a loaded up EC135 or MD902 because it has FEWER systems. Fewer systems to malfunction means fewer things that can go wrong and fewer things that the pilot has to screw up. Right??? Man, I have GOT to be misunderstanding you. All the advances in technology have only brought us backwards then right? Come on man, you can't actually believe that. In this case, less is not more.

Edited February 24, 2011 by Wally

[Oil Pilot]

You have, or you will at some point, shut down the wrong system in a twin.

 

Don't get me wrong, I'm certainly not invulnerable, but with proper training and the advanced indication systems in today's twins, this does not have to happen.

 

I'm assuming from your statement that you can find us multiple accounts of this happening on the NTSB website and causing an accident. I'll be here waiting.

[Gomer Pylot]

If you look carefully at the NTSB reports, you'll see that few people die because of engine failures in single-engine helicopters. Most people die from hitting hard objects at high speed, often from loss of control in IMC conditions. Which is safer depends entirely on your definition of safer. Twins might be able to continue flying after the loss of an engine, but not all can. Try losing an engine in a BO-105 at max gross weight, and see how long you stay in the air. In a single, you know, absolutely, that you have to autorotate if the engine quits, so it's instinctive to lower the collective and autorotate. In a twin, you have a lot more to think about, and people have died because they got in a rush and pulled off the good engine. Having more systems, inclluding autopilots, can cut both ways, and the autopilot will kill you very quickly if you don't use it properly. You have to know the systems, and know how to use them under all circumstances, and make the right decisions at the right times, and that can be difficult.

 

I've never seen any statistics, anywhere, that indicate that twins are safer than singles, as long as you're talking about surviving. A higher percentage of accidents in twins are fatal, although there are a few more accidents in singles caused by engine failure. Not nearly as many as you might think, though, and very few are fatal. Some bent metal isn't that big a deal for a pilot, and that's all that usually results after an engine failure in a single.

 

Safety depends on much, much more than the number of engines. The truth is that twins have more fatalities than singles, when compared on a basis of accidents/flight hour. All I care about, really, is staying alive. The numbers indicate that the chances of that are better in singles. That said, I'll take a twin, with two pilots and full IFR capability and a full flight director, if I have the choice. Flying an S76C++ in IMC is fun, and a lot more comfortable, than flying a 206, no doubt. But it's not that much more likely to keep me alive. Claiming that twins are necessary for safety is either disingenuous or ignorant.

[Spike]

After realizing the risk I’ve been taking over the years flying a single over mountainous terrain, especially at night, I finally decided to do something about it. So I marched into the boss’s office and demanded we purchase a twin! He looked at me as if he was seriously constipated at told me to get the “f” out of his office.

 

Somewhat bewildered, I thought I must have approached the subject incorrectly so I compiled a twin vs. single engine helicopter analysis PowerPoint presentation and marched back into the boss’s office…. During the presentation, I don’t think he ever looked at the screen. He just looked at me with that same look on his face and before I could get to the fourth panel, he threw a raggedy 2004 FAR/AIM at me and again told to get the “f” out of his office.

 

Totally bummed at the start of my shift last night and with the fear of death looming, I thought I’d try to convince the boss one last time. This time I politely knocked on the door and asked of I could speak with him. “As long as you’re not going to give me that twin BS!” he said. So I tiptoed in and approached the subject with subdued reasoning about the increased safety margin with twins. This time, the boss had a mischievous little smirk and said; “Spike, when you applied for this job, you knew we flew singles, right? And, you knew we flew over mountainous terrain at night, right?” I said, yep… He then added, “If we were to purchase twin engine helicopters, your salary would be half of what it is! Is that what you’d want?” I replied, HELL NO!

 

So last night while flying over that mountainous black hole I was happy as a clam knowing I had a job that paid me well.. And the reality is I don't get to choose. I’d like to fly a twin but I get paid to fly a single………..

Edited February 24, 2011 by Spike

[Oil Pilot]

The truth is that twins have more fatalities than singles, when compared on a basis of accidents/flight hour.

 

Any data to back that up?

 

Since 2006 there have been 232 fatal accidents according to the NTSB. 28 of those accidents have been in twins. So we're saying twins make up less than 12 percent of the total flight hours in helicopters?

 

Oh look, someone got some more data.

 

http://www.justhelicopters.com/Default.aspx?tabid=410&EntryID=4

[Wally]

Don't get me wrong, I'm certainly not invulnerable, but with proper training and the advanced indication systems in today's twins, this does not have to happen.

 

I'm assuming from your statement that you can find us multiple accounts of this happening on the NTSB website and causing an accident. I'll be here waiting.

 

No accident "has to happen", although some factors do raise the risk. It's my opinion the stats on single vs twins show that the extra systems involved outweigh the benefit of power redundancy.

Advanced indicating systems are spreading throughout the fleet, single and twin. Opinion- well presented and accessible information is more important with more complex systems- like twins.

 

There isn't a number of engines or pilot error search criteria on the NTSB website... How to do this presenting common knowledge as an evaluation tool? Okay- If the number of engines were the critical safety advantage it is perceived to be, then the 206 would not have been the safest helicopter in the world at any point in it's history, as light twins flew the same jobs. It's even been posited that the 206 is/was the safest single engine aircraft of any type by some.

Edited February 24, 2011 by Wally

[JDHelicopterPilot]

I am not even going to get into this to deep. Each has it's pros and cons. Each (pilot or operator) needs to weigh them and decide which aircraft best fits their flying profile.

 

I would proably draw the line though at flying a single in the mountains with no NVGs. I would either want NVGs or a twin. Otherwise my routes I take at night would be quite limited.