Whilst I have to accept your statistics I’m not sure where they come from.
How has anybody managed to collate the number of hours that have been flown in twins or singles to get the figure of X or Y number of fatalities per 100,000 hours.
Then you have the conditions in which the aircraft are flown. How many of the 100,000 hours flown either in a twin or a single are flown in IMC or at night.
A loss of an engine in most twins are a non event and if the pilot is well trained should not lead to a loss of control. You fly on with one engine, you land with one engine. Why would a twin engined aircraft spin in from 5000 ft, why didn’t the instructor reduce power on both engines, recover from the spin in the normal manner eg opposite rudder, neutral ailerons and stick forward until vyse is achieved whilst cleaning up any drag and feathering the prop, then level off and either full power on good engine or more usually the power setting one above the usual power setting eg 90% instead of 70%. There were problems in the training environment with light twins like the twinkie, usually from Vmca demonstrations at low altitudes and so this was banned or at least not recommended in all twin training. It is also why EFATO is usually briefed as both engines to zero immediately and land.
You have an engine failure in the cruise in a single and the only way is down, even if you have a parachute, although the chute makes a fatality, less likely.
The one thing I would agree with is that if the statistics say that if you do crash a twin the fatality rate is likely to be higher. The same if you crash a 737, or an A320. One reason could be that there are likely to be more people on board.
Are there any statistics that show, the heavier the aircraft the more likely you are to die in a crash? In which case the answer must be a ULM or something under 600kg being tje safest aircraft to fly 🙃
gallois wrote:
Are there any statistics that show, the heavier the aircraft the more likely you are to die in a crash?
Just the laws of physics. The heavier a plane is, in general (there are some exceptions, e.g. the An-2) the higher the minimum flying speed. A 2000kg light twin is likely to have a much higher stall speed than a 600kg ULM or even a 1200kg light single, and will take more space to stop if landed off-airport (even if the stall speeds are the same, due to the additional kinetic energy you have to get rid of).
Given that most fatal accidents happen with a perfectly functional engine but with some kind of loss of control (and in twins, two perfectly functional engines), extra engines is rather a lesser contributor to a safer flight than other things. (And when an aircraft does crash with a stopped engine, there is a fairly high chance it was because there was too much air in the fuel tanks, which will bring a twin down as surely as it will a single…but now with a bunch of extra kinetic energy that you have to get rid of in some sheep paddock)
The number of flying hours is clearly an approximation, but it’s close enough approximation that a difference between 1.6 fatalities per 100k flight hours versus 2.04 per 100k is simply not going to be explained away by sampling error.
The heavier the plane, the better it will penetrate through trees and other obstacles, lowering the acceleration imposed on the occupants.
The best combination for safety is a heavy vehicle and a good structural cage around the occupants. But you need both.
Low impact speed is good. Not all twins stall at higher speed than all singles.
alioth wrote:
that a difference between 1.6 fatalities per 100k flight hours versus 2.04 per 100k is simply not going to be explained away by sampling error.
Sure, but it is a completely meaningless number; the question is “what is safer __for my mission_ – a single or a comparable twin”.
If I want to fly IFR in poor weather and am thinking about Malibu, C210, SR22 or Bonanza vs Seneca, Cessna C3xx or 4C, or Baron, the low stall speed of a Cub or C150 and the accident rate of Seminoles in training is completely irrelevant.
And given that most accidents in this kind of operations (flying in weather too bad to handle, CFIT and so on; also running out of fuel) are pilot induced, I think the answer is NEITHER is safer to any significant degree.
Silvaire wrote:
The heavier the plane, the better it will penetrate through trees and other obstacles,
… and the faster it will still be after having made its way through the bushes and hitting the hard ground.
Silvaire wrote:
The best combination for safety is a heavy vehicle
This is true for cars that basically move in 2D in an environment where only in few cases the movement will finally end at a hard structure which is more or less perpendicular to the direction of movement (aka “wall”). So the main deceleration happens exactly when penetrating the underwoods. When a car directly hits a concrete wall or a major tree the weight doesn’t make much of a difference and it is only about stability of the “cage”.
For an airplane the crash mechanism is different: It typically hits a hard structure that is more or less perpendicular to the direction of movement and is only to a small extend slowed down by the fauna it penetrates before. In those situations less energy is better.
alioth wrote:Therefore, statistically, twins are quite a bit more dangerous than singles
Statistically comparing the total average fatality rates in different types of airplanes is as useful as calculating the specific weight of haggis: You just mix together too many things to get a meaningful insights.
Without any reasonable doubt flying traffic patters with touch and goes are much more risky in a twin than in a single. With the same lack of doubts, flying 1000NM over cold water is much more risky in a single than in a twin. Everything in between is pretty much depending on the specific situation.
But what is true in any case: Engine failure is much more a psychological issue than a real one. Yes, they do happen, but compared to fatalities by human errors they very rarely lead to fatal accidents.
P.S.: Ending a Spin in a dual engine plane which is not a Skymaster is indeed more difficult than in a single because the moment of inertia around the roll axis is much higher due to the weight of the engines which is far away from the axis.
Malibuflyer wrote:
For an airplane the crash mechanism is different
I hope you can continue to create crash scenarios in your imagination and apply them to any future experience, but in the real world I’ve already flown an aircraft to the ground unwillingly, ending up with a broken plane in a rough area, and oddly enough it was quite different than you propose 
No point mixing aggregate fatality rates, you have to “convolute” against your OWN flying mission
I had an EFATO once in 500m strip at 100ft, I am glad it was in the Cub not DA42 or some 1.5T touring SEP, it’s just one example to think of…
I agree with Cobalt neither is safer in absolute terms
Guys, comparing flying hours of twins with those of singles leads nowhere. I didn’t read the whole thread, it was surely pointed out already. But you fly a Twin in another mission than a Single. So typically the risk is higher, e.g. more severe weather conditions. And then if the pilot has not the necessary experience, it doesn’t matter whether he’s flying a single or a twin. But as in these conditions more often twins are used (might even be linked together, as only pilots with big balls fly hard IFR in a single, so those pilots flying Twins must have …) they achieve a higher accident rate.
I honestly do not think that a Twin could in any respect be called “unsafer” over a Single (if flown above minimum speed). They’re just taken to missions, where the pilot shouldn’t go.
The additional engine helps avoid abortion of flight due to technical reasons. However, technical reasons are very rare – among the reasons leading to abortion of flight.
gallois wrote:
Why would a twin engined aircraft spin in from 5000 ft, why didn’t the instructor reduce power on both engines, recover from the spin in the normal manner eg opposite rudder, neutral ailerons and stick forward until vyse is achieved whilst cleaning up any drag and feathering the prop, then level off and either full power on good engine or more usually the power setting one above the usual power setting eg 90% instead of 70%.
The trap is the instructor thinks safety equates to altitude and carries out a Vmca demonstration at altitude, not realising that Vmc, due to lower max power on the live engine, is now well below Vso. This inevitably leads to a high rotational flat spin, which in certain types is unrecoverable. This is why the FAA introduced the concept of Vsse for Vmca demonstrations, a concept which doesn’t appear to be well understood in EASA land.
Why is the flat spin unrecoverable, the alpha is so high, over 40 degrees, that the rudder is no longer effective. Powering out asymmetrically will not overcome the autorotational forces, nor reducing power to idle, nor feathering, etc
@Cobalt I think the poster child is the safety record between the King Air and the PC-12. Here we have similar missions, with professional crew (in some cases crews), and the PC-12 enjoys a better safety record. The advantage is possibly marginal, but combined with the economics this led to the marketing segmenting between the PC-12 and the KA350, and sales of the 90/200/250 reducing.
I know two crews, professionally trained and current, who were lost to a KA engine failure and LOC.
