Can we put the myth that singles are as safe as twins to bed now?
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Can we put the myth that singles are as safe as twins to bed now?
From another forum: 93% of non commercial accidents are in singles, 7% are in twins. The FAA says that singles are flown 12.16 million hours per year and twins are flown 1.82 million hours per year in the US. That means that singles have twice as many accidents per flying hours as twins.
Wherever that figure that we've heard bandied around for the last decades comes from, I don't know (Dick Collins, I'm looking at you), but they're not true according to these documents:
http://www.aopa.org/-/media/Files/AO...02011_2012.pdf
General Aviation and Part 135 Activity Surveys - CY 2010
Wherever that figure that we've heard bandied around for the last decades comes from, I don't know (Dick Collins, I'm looking at you), but they're not true according to these documents:
http://www.aopa.org/-/media/Files/AO...02011_2012.pdf
General Aviation and Part 135 Activity Surveys - CY 2010
Last edited by AdamFrisch; 4th Jan 2014 at 03:32.
According to your first link, page 6, 23/82 or 28% of twin accidents were fatal, but 141/883 (16%) single fixed-gear accidents were fatal. 66/229 or 28% of accidents in single-engine retractibles were fatal.
Your twins may or may not be half as likely to be in an accident, but if you do then you're about twice as likely to be killed in said accident. On the other hand, perhaps it's fairer to compare the single engine complex aircraft to the twins. But we don't have enough information to do that.
Then, you would expect your average twin pilot to be considerably better trained than your average sep pilot. So if you're about equally likely to be killed in a twin or a single, then it probably implies that twins are more dangerous.
So no... not settled.
Your twins may or may not be half as likely to be in an accident, but if you do then you're about twice as likely to be killed in said accident. On the other hand, perhaps it's fairer to compare the single engine complex aircraft to the twins. But we don't have enough information to do that.
Then, you would expect your average twin pilot to be considerably better trained than your average sep pilot. So if you're about equally likely to be killed in a twin or a single, then it probably implies that twins are more dangerous.
So no... not settled.
Last edited by abgd; 4th Jan 2014 at 03:56.
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The figures I kept hearing were always accidents, not fatalities. Which in this case is in favour of twins. It is reasonable to get a higher number of fatalities in a faster moving aircraft. But it's muddled, I'll give you that.
As with most things in life, things are never simple.It depends what you're saying...are the aircraft themselves inherently less safe ( so with the same quality of pilot, weather, airport etc and training) the SEPs would have more accident, or that th SEP category is operated in a manner which attracts more incidents? This was one of abgd's points. There are so many external factors that itwould be impossible to categorically say one way or the other. Aaah, statistics, eh?
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Adam I think looking at the type of equipment used for the accident numbers is misleading.
If you take a sampling of say 100 GA pilots, probably no more than 10% fly twins, I would guess that the vast majority of that 10% in addition to having MEP training will have Instrument and maybe even commercial or some other advanced certificate like ATP and some type of recurring training program even if they are non commercial flyers. Where as i suspect that the other 90% of GA pilots who fly singles stopped there official training path upon receipt of their PPL with just flight reviews as further "training".
If you looked at the the equipment (SEP/MEP) from purely a hardware reliability standpoint like you would any other machinery the mean time to failure providing both get similar maintenance is probably not that far apart.
Like most things in life, it's the the operator that is the weak link and usually due to training.
If you take a sampling of say 100 GA pilots, probably no more than 10% fly twins, I would guess that the vast majority of that 10% in addition to having MEP training will have Instrument and maybe even commercial or some other advanced certificate like ATP and some type of recurring training program even if they are non commercial flyers. Where as i suspect that the other 90% of GA pilots who fly singles stopped there official training path upon receipt of their PPL with just flight reviews as further "training".
If you looked at the the equipment (SEP/MEP) from purely a hardware reliability standpoint like you would any other machinery the mean time to failure providing both get similar maintenance is probably not that far apart.
Like most things in life, it's the the operator that is the weak link and usually due to training.
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Also, how many of those single accidents were in aerobatic types. Clearly this kind of flying far more likely to end in an incident that your usual twin transit.
Unless the data can be broken down in further detail, then as usual, the stats are not accurate enough to be precise.
Unless the data can be broken down in further detail, then as usual, the stats are not accurate enough to be precise.
93% of non commercial accidents are in singles, 7% are in twins.
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On the whole pilots who fly singles range from very experienced competant and current to complete idiots who should not be allowed to fly a kite and there are a whole mass in between.
While the same probably applies to MEP pilots the idiot section is probabaly a lot smaller.
We all Know the benefits of flying a twin over fog, at night, low cloud over water etc but its when the one engine fails that the twin pilot does not fare so well but for me that is a currency and training issue.
A twin has more power and in my book power is safety.
So yes I am sure with both engines running a twin is more capable and safer other than when you move to top of the range singles
Pace
While the same probably applies to MEP pilots the idiot section is probabaly a lot smaller.
We all Know the benefits of flying a twin over fog, at night, low cloud over water etc but its when the one engine fails that the twin pilot does not fare so well but for me that is a currency and training issue.
A twin has more power and in my book power is safety.
So yes I am sure with both engines running a twin is more capable and safer other than when you move to top of the range singles
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Also comes into this is the number of rotations.
Surely SEP aircraft fly largely 40-60 minute sorties, so have a high number of take offs and landings, which are clearly the most safety critical part of the flight.
Twins on the other hand will fly 2 hours or more as a typical flight, long times spent in the cruise, possibly even on autopilot, all skews the figures, so you can't directly compare the two as they are operated so differently.
It's impossible to reach a meaningful conclusion, even with all the stats.
Surely SEP aircraft fly largely 40-60 minute sorties, so have a high number of take offs and landings, which are clearly the most safety critical part of the flight.
Twins on the other hand will fly 2 hours or more as a typical flight, long times spent in the cruise, possibly even on autopilot, all skews the figures, so you can't directly compare the two as they are operated so differently.
It's impossible to reach a meaningful conclusion, even with all the stats.
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I think the basic facts speak for themselves. You are more likely to have an accident in a single than a twin, however you want to bend the stats. Makes sense as well, you have redundant systems on a twin.
IF an engine fails in a twin and IF it is handled correctly, it could be no more than an inconvenience at worst. IN a single, you ARE going down. If you are lucky you will pull off a decent off airport landing with no damage, if you are exceedingly lucky you will land back on a runway and if you are unlucky you might die or destroy the aeroplane.
IF an engine fails in a twin and IF it is handled correctly, it could be no more than an inconvenience at worst. IN a single, you ARE going down. If you are lucky you will pull off a decent off airport landing with no damage, if you are exceedingly lucky you will land back on a runway and if you are unlucky you might die or destroy the aeroplane.
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I agree -- the issue is complex and not easily answered.
Lies, Damned Lies and Statistics -- Mark Twain
The airlines are really good when the statistic is fatalities per passenger mile -- helps to have a couple hundred bods behind and only do long flights
A metric that may be less biased is fatal accidents per flight, but that number in the GA fleet is a matter of extrapolation from hours flown -- hence unreliable.
We can look at accident reports to gain a sense of specific accident factors, especially those that kill people.
A metric that may be less biased is fatal accidents per flight, but that number in the GA fleet is a matter of extrapolation from hours flown -- hence unreliable.
We can look at accident reports to gain a sense of specific accident factors, especially those that kill people.
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"We all Know the benefits of flying a twin over fog, at night, low cloud over water etc but its when the one engine fails that the twin pilot does not fare so well but for me that is a currency and training issue.
A twin has more power and in my book power is safety."
Yes, but how many twin pilots appreciate that when one engine fails they can lose as much as 90% of their excess power. Excess power being the power in excess of that needed to maintain straight and level flight. This is worth reading:
Accident Prevention Program
A twin has more power and in my book power is safety."
Yes, but how many twin pilots appreciate that when one engine fails they can lose as much as 90% of their excess power. Excess power being the power in excess of that needed to maintain straight and level flight. This is worth reading:
Accident Prevention Program
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something else to consider.....the twin is a damned sight heavier than s single with similar pax. capacity...and to play devil's advocate....there are a fair number of singles with light structure, light wing-loading and slow flight characteristics....the twin is generally faster. yes, I'm aware the new light composites are very slippery and appear to have little redundant strength-margins, but they're not a significant percentage of the GA fleet, are they?
Are 3-axis Microlights included?
Figures are pretty meaningless unless there area lot more specific parameters attached to the results, however, it would be interesting to see these various sub-categories analysed by number of flights and total flight-hours, average flight -hours etc. I have a sneaking suspicion that Regulated Flexwings are the safest powered, other than Powered gliders....
Are 3-axis Microlights included?
Figures are pretty meaningless unless there area lot more specific parameters attached to the results, however, it would be interesting to see these various sub-categories analysed by number of flights and total flight-hours, average flight -hours etc. I have a sneaking suspicion that Regulated Flexwings are the safest powered, other than Powered gliders....
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while I don't have the figures to back it up, I've seen twins get into trouble not so much on takeoff, but in descent.
You know right away if an engine quits on takeoff.
But in a descent, you might not notice (at a lower power setting) until you level off in the circuit/pattern for the downwind. I saw a video of a 421 augering in near chicago losing one on the descent.
Twins are nicer, but only if you are ready to fly with one shut down. I mean nicer in that they are usually better equipped.
You know right away if an engine quits on takeoff.
But in a descent, you might not notice (at a lower power setting) until you level off in the circuit/pattern for the downwind. I saw a video of a 421 augering in near chicago losing one on the descent.
Twins are nicer, but only if you are ready to fly with one shut down. I mean nicer in that they are usually better equipped.
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I have about 800 hrs in single pistons and 3000 hrs in piston twins! i would never dream of flying some of the weather I have flown in the twins in a single! icing, at night, over long stretches of water, over fog banks, low cloud and strong winds and turbulence.
Ok a twin is a real aeroplane
and a single a toy for nice days 
unless its a TBM 850 or Pilatus PC12
Pace
Ok a twin is a real aeroplane
and a single a toy for nice days unless its a TBM 850 or Pilatus PC12 Pace
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it only turns into a real plane pace when it has a toilet fitted. And one that flushes at that 
Or it can pull over 3g
PS only teasing I love flying cubs and the like. Well actually anything that's fly's and I can fit my arse into. It doesn't need to have an engine.
Or it can pull over 3g
PS only teasing I love flying cubs and the like. Well actually anything that's fly's and I can fit my arse into. It doesn't need to have an engine.
Last edited by mad_jock; 5th Jan 2014 at 06:41.
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MJ
I was half teasing I think it is hard to compare as a twin and single USUALLY have a different mission profile and the pilots USUALLY tend to be more experienced ! I stress the word usually as there can be very experienced capable pilots who fly singles in **** 
Most singles are not equipt for serious weather flying a case of different horses for different courses
Pace
I was half teasing
I think it is hard to compare as a twin and single USUALLY have a different mission profile and the pilots USUALLY tend to be more experienced ! I stress the word usually as there can be very experienced capable pilots who fly singles in **** Most singles are not equipt for serious weather flying a case of different horses for different courses
Pace