Ian Johnston wrote:

About 3000 people in the UK die in road accidents each year. Assuming
that almost all the population uses roads in some way, that;s 3000 out
of 60 million, which is 1 in 20000.

If the average person lives to the age of 80, it follows that 1 in 80
of the population dies each year anyway (from all causes). Thus you'd
expect 1 in 700000 of the population to die in any hour.

If the average person spends 200 hours a year on the roads, you'd expect
1 in 3500 of the population to die on the roads each year (from all causes).

If in addition 1 in 20000 die from road accidents per year, this suggests
6 in 7 of all road deaths are non-accidental.

Of the 5000 or so glider pilopts
in the UK, about 5 die flying annually which gives a death rate per
annum of 1 in 1000.

You'd still expect 1 in 700k gliders to die each hour simply because they
are part of the general population. And if they spend 20 hours per year
in the air, you'd expect 1 in 35k of gliders to die in the air each year.
If in fact 1 in 1000 die in gliders each year, you'd expect only 1 in 35
air deaths to be non-accidental.

Doesn't that make gliding 30 times as dangerous as being on the road?

In article ,
ldomain says...


Doesn't that make gliding 30 times as dangerous as being on the road?

On an hourly participation basis, that is probably reasonable.

When I used to glide, I once worked out that for an under-40 male, being
a driver roughly doubled your annual mortality risk, and gliding roughly
doubled it again. But on a hourly basis, gliding is certainly more risky
than driving.

When I used to glide, I once worked out that for an under-40
male, being
a driver roughly doubled your annual mortality risk, and gliding
roughly
doubled it again. But on a hourly basis, gliding is certainly
more risky
than driving.

OK. Did some research from US statistics, causality alone, 2002,
all within 20% (cos I'm a back of an envelope person first time
round):
-------------------------------------

Cars.

38,000 deaths pa, (10 times as many injuries).
15 per 100,000 population (UK, about 7/100,000)
1.5 per 100,000,000 miles
4.5 per 10,000,000 hours

Source: http://www-fars.nhtsa.dot.gov/
--------------------------------------

Boats (12,000,000 - of which sail and Aux sail 40%)

Deaths pa 800 (5 times as many injuries)
0.25 per 100,000 of population
7 per 100,000 boats
2.8 per 10,000,000 hours (heroic assumption; 250hrs per boat pa)
However: sailboats are only 1% of deaths!

Source:
http://www.uscgboating.org/statistic...stics_2002.pdf
---------------------------------------

General Aviation (220,000 aircraft, 30,000,000 hours flown)

Deaths pa 600 (1,800 accidents)
0.7 deaths per 100,000 population
270 deaths per 100,000 aircraft
200 deaths per 10,000,000 flying hours

Source: http://www.ntsb.gov/publictn/2004/ARG0401.pdf
----------------------------------------------

First, don't shout about the detail. I said within 20%. Now, some
points of interest:

1. I'm very surprised that US stats show nearly twice as many
road deaths as UK per whatever. Also the small motor boat death
rates in US are far higher as a proportion than in UK.

2. I'm now quite clear why insurance rates for general aviation
are so high, and why boat insurance is similar to car insurance
rates.

3. I think on a per hour basis, car driving in UK is about quits
with boats, though sailboats may be safer! That would take more
research, and I'm in Easter Holiday trouble already.

4. None of this takes account of person to person skill
variations. Surveys have routinely shown that 80% of car drivers
believe that their skills are above the average, if not
exceptional. Pilots are similar. I've never asked sailors - just
examined them. So I've got a good idea what the average skill
levels of examinee sailors are - and they're the skilled minority.
My view is that the personal skill levels are not relevant to boat
safety - I think 'fear factor' is more important. Avoiding things
you can't do, or being very careful when trying them. Most boat
deaths are due to not wearing buoyancy aids, or being under the
affluence of incohol (see reference).
--
JimB
http://www.jimbaerselman.f2s.com/
Describing some Greek and Spanish cruising areas

On Mon, 17 Apr 2006 13:03:18 UTC, "News f2s"
wrote:

: 2. I'm now quite clear why insurance rates for general aviation
: are so high, and why boat insurance is similar to car insurance
: rates.

In the first case it's not just, or so much, the frequency of the
accidents, but the possible claims involved. Hit a 747 on the ground
in your Cessna and the bill can easily be tens of millions.

Ian

--

"Ian Johnston" wrote in message
news:cCUlhtvFIYkV-pn2-h1QXuVTzjBkd@localhost...
On Mon, 17 Apr 2006 13:03:18 UTC, "News f2s"
wrote:

: 2. I'm now quite clear why insurance rates for general
aviation
: are so high, and why boat insurance is similar to car
insurance
: rates.

In the first case it's not just, or so much, the frequency of
the
accidents, but the possible claims involved. Hit a 747 on the
ground
in your Cessna and the bill can easily be tens of millions.

Hmm. These actuaries are pretty bright at their numbers. How many
Cessnas have hit 747s? But I take your general point that
aviation accident costs are much higher per incident. To a degree
that's covered (in insurance terms) if your insurance rates are
charged as a percent of vehicle value.

Quite simply, if any individual GA aircraft has 40 times the
probability of killing someone per annum, I'd expect the premium
to be 40 times higher. Crude. So load by the average value damage
done (compared to a boat) which would be quite a lot higher, x10?
So I wouldn't be surprised to hear that boat insurance runs around
1% to 2% of craft value, while airplane insurance runs around 10%
of value. Roger Long would know if that's the right order - he's
instigated several threads suggesting that aviation insurance
rates may come to boats! Someone here would know.
--
JimB
http://www.jimbaerselman.f2s.com/
Describing some Greek and Spanish cruising areas

On Mon, 17 Apr 2006 11:35:04 UTC, Ronald Raygun
wrote:

: Ian Johnston wrote:
:
: About 3000 people in the UK die in road accidents each year. Assuming
: that almost all the population uses roads in some way, that;s 3000 out
: of 60 million, which is 1 in 20000.
:
: If the average person lives to the age of 80, it follows that 1 in 80
: of the population dies each year anyway (from all causes). Thus you'd
: expect 1 in 700000 of the population to die in any hour.

You'd expect that anyway, from the average lifespan being about
700,000 hours. But maybe that's what you meant?

: If the average person spends 200 hours a year on the roads, you'd expect
: 1 in 3500 of the population to die on the roads each year (from all causes).

You are assuming, though, that "being on the road" and "being likely
to die of natural causes" are independent, which is quite definitely
not the case. In addition, the 3,500 deaths per year does not, as far
as I am aware, count people who have heart attacks on buses and so on
- it's people who dies as a result of road accidents.

: If in addition 1 in 20000 die from road accidents per year, this suggests
: 6 in 7 of all road deaths are non-accidental.

.... and, as per above, not counted in the 3500.

: Of the 5000 or so glider pilopts
: in the UK, about 5 die flying annually which gives a death rate per
: annum of 1 in 1000.
:
: You'd still expect 1 in 700k gliders to die each hour simply because they
: are part of the general population.

Neither "being a glider pilot" nor "dying of natural causes" are
evenly distributed, and they are not independent. Would you expect 1
in 700,000 of both schoolchildren and octogenerians to die every hour?

: Doesn't that make gliding 30 times as dangerous as being on the road?

It's certainly a lot more dangerous, but I don't think your
statistical approach demonstrates how much more dangerous.

Ian