Risk compensation

fabian wrote:

There is a peak accident rate for non IR pilots at around 500 flight hours. Which means that until this point risk keeps increasing, and many pilots never actually pass over this peak within their flying career

This is at least semantically wrong, and also does not give any indication of the risk. What is plotted is the hazard in the risk equals hazard times exposure – equation. Risk is literally like throwing a dice each flight hour to see if you survive or not, and adding as you go. Thus, when starting with zero flight hours, the only sure thing is that the longer you plan to fly, TFH, the higher the risk. The total risk will never decrease.

What the graphs show (and they are very interesting indeed), is the probability of an accident your next flight hour, given you actually have survived all the previous flight hours. The point is however, that risk vise, the probability that you actually have survived until your next flight hour, is much, much lower than the probability you will survive your next flight hour. Your next flight hour is always lower in risk, than your previous flight hours (with the exception of zero or one previous flight hour).

The best method to reduce the risk, is to reduce the TFH. It’s as simple as that. A reduction of the exposure is always an easy and straight forward risk reduction method that works every time. But of course, reduction of exposure is a pretty meaningless method for recreational GA (except for EASA I guess). Nevertheless, having all VFR pilots flying 2000 hours for the purpose of reducing risk among recreational GA, is complete nonsense talk.

LeSving wrote:

This is at least semantically wrong, and also does not give any indication of the risk. What is plotted is the hazard in the risk equals hazard times exposure – equation.

If we are going into semantics, the proper terminology when you are working with risk analysis is (briefly put) this:

Hazard — A situation that can lead to an undesirable outcome (basically a “threat” situation).
Risk — The “expected value” of an undesirable outcome, typically obtained by multiplying the probability of the outcome with a quantification of its effect.

I would argue that I actually meant a risk, but didn’t really go into much detail about it ;-) : Each point in the given model represents the rate of accidents for 100 flight hours flown within a year. That will become more clear if you take a look at the paper. Of course it does not represent the lifetime risk, or a risk for an exposure different from 1yr with 100 flight hours. An estimation method for that is actually also provided in eq. 14, if you are interested ;-)

The resulting rates were then divided by 4.65 to represent
one average year’s rates before starting the curve-fitting process.
Keep in mind that the height of the y-axis represents the probability
of having an accident over a 100-FH span, x±50

To estimate the relative accident rate for a given value of
THF=x, (meaning the range from x-50 to x+50, flown over the
course of 1 year)

But maybe I’ve missed something, after all im a physics guy and not from the area of risk management ;-)

fabian wrote:

Each point in the given model represents the rate of accidents for 100 flight hours flown within a year.

OK, just trying to get this sorted out in my head. Risk is not a rate, not a per hour thing IMO, it’s just a probability factor when the exposure is known. GA is simple. either you are still alive (or well enough ) to fly the next flight hour, or you are not. If you fly 100 hours per year, and the probability of a fatal accident is 0.005 for those 100 hours, than the probability of you surviving those 100 hours is 0.995. The probability of surviving one flight hour becomes 0.99994988. The probability of surviving 10 flight hours becomes 0.9994989.

If you plan to fly 100 hours, the risk of dying is 0.5 % those hours. If you plan to fly 10 hours, the risk of dying those 10 hours is only 0.0501 %, or approximately 1/10. Rather obvious, since you are exposed to the risk only 1/10 of the time.

This is pure numbers. It doesn’t take into account that we are different and that lunatics die sooner rather than later. Lets’s say we have 10 pilots. 9 are average with a 0.99995 chance of surviving each hour, and one is complete lunatic with only 0.95 chance. After the first 100 hours, the normal pilots have 0.995 chance of surviving, while the lunatic only has 0.006 chance of surviving. Thus, after 100 hours, the lunatic is most probably dead. On average (considering every tenths is a lunatic), the probability of a fatal accident the first 100 hours is approximately 0.1 or 10 %. But since the lunatics most probably are dead after the first 100 hours, then the next 100 hours will show a statistic that is closer to 0.005 fatal accidents again. IMO, the simple fact that people die, and lunatics die sooner rather than later, can very well explain your curves. Risk compensation and so on, may very well be dead end explanations. It may have nothing to do with it.

Is it a dumb thing to say that managing the risk is at least part of the fun of GA flying?

LFHNflightstudent wrote:

Is it a dumb thing to say that managing the risk is at least part of the fun of GA flying?

Given we are talking the risk of death or serious injury, yes it is.

JasonC wrote:

Given we are talking the risk of death or serious injury, yes it is.

Absolutely. Ever seen someone with real bad injuries or burns? No “fun” of whatever kind and especially no recreational activity is worth that. Therefore we (I at least) try to keep the risk at the lowest possible level.

My question was about managing the risk, not taking unnecessary risks. We all fly (as safely as possible I hope) and are conscious of the risks that implies. Yet we still do and enjoy it. For me at least managing those risks so they are minimal is part of the fun. Does that make more sense?

LFHNflightstudent wrote:

Is it a dumb thing to say that managing the risk is at least part of the fun of GA flying?

Managing personal risk of various kinds, physical, financial and including risks in aviation is most of my enjoyment in life and it’s how you succeed where others can’t or don’t.

Of course it makes sense, humans are made that way – whether they for some reason dislike admitting it, or not.