homebuilt safety

I'd be grateful if anyone can direct me towards links about the relative
safety of different types of homebuilt aircraft. Not figures I can use to
prove to myself that flying a homebuilt is safe, but a discussion of all
the factors that affect safety in homebuilt aircraft. I haven't found much
through google - perhaps it's a contentious subject?

Though I realise that most of the safety equation is down to the pilot,
presumably some types have safer flying characteristics than others? And
presumably crashes in some types are more survivable than crashes in
others in the same way as some car-wreck scenarios that would have been
lethal 20 years ago are easily survivable today?

AC

In my opinion, the majority of accidents are the result of human error:
Running out of fuel, running into the ground, running into other planes,
flying into instrument conditions without training (and then losing
control) and the like. Certified versus experimental-amatuer built
status has little to do with these human factors.

If you are looking for a "volvo in the sky" I cant offer much to you.
Trying to derive a relative safety equation is an apples to oranges
affair unless you can account for hours flown per type, pilot experience
and other factors for which the data isnt routinely sampled and available.

The EAA (www.eaa.org) may be a good source to look at for
charactaristics of certain homebuilts. I seem to remember seeing reviews
of some types of homebuilts in their Sport Aviation publication. They
evaluated things such as static and dynamic stability, control forces,
maneuvering characteristics and the like.

The NTSB (www.ntsb.gov) has accident reports available, and searchable,
for several decades. You can look and see what seems to be the most
common causes of accidents for yourself... by type, by date, by
region...etc.

Dave

anonymous coward wrote:
I'd be grateful if anyone can direct me towards links about the relative
safety of different types of homebuilt aircraft. Not figures I can use to
prove to myself that flying a homebuilt is safe, but a discussion of all
the factors that affect safety in homebuilt aircraft. I haven't found much
through google - perhaps it's a contentious subject?

Though I realise that most of the safety equation is down to the pilot,
presumably some types have safer flying characteristics than others? And
presumably crashes in some types are more survivable than crashes in
others in the same way as some car-wreck scenarios that would have been
lethal 20 years ago are easily survivable today?

AC

Somewhere, a long time ago, I was told the number one problem that
occures with homebuilts is fuel system related.
How true that is today, I do not know.
Nowadays, the aircraft are faster and the pilots less experienced.

On Fri, 14 May 2004 22:31:56 +0100, anonymous coward
wrote:

I'd be grateful if anyone can direct me towards links about the relative
safety of different types of homebuilt aircraft. Not figures I can use to
prove to myself that flying a homebuilt is safe, but a discussion of all
the factors that affect safety in homebuilt aircraft. I haven't found much
through google - perhaps it's a contentious subject?

Though I realise that most of the safety equation is down to the pilot,
presumably some types have safer flying characteristics than others? And
presumably crashes in some types are more survivable than crashes in
others in the same way as some car-wreck scenarios that would have been
lethal 20 years ago are easily survivable today?

AC

David Thurston wrote a book called "design for safety"
heavens! published by tab books 9 years ago.

homebuilts are usually lighter in weight which makes them quicker to
move in turbulence. control forces are usually quite light.
they arent any weaker. most designs are built to the same "g" range as
commercial designs.
every homebuilt is a one off constructed aircraft. it has subtle
differences from every other homebuilt ever built. as well they are
usually lighter built. keep all the switches

I took over a hundred hours to get really comfortable in my homebuilt
but now I wouldnt want to go back to commercially produced aircraft.
persist and you will grow to love the quick responsive flight
characteristics.

things break occasionally. I've lost the tailwheel 3 times now and I
am gradually evolving the design. I think I have it just about right
at last.
you can do that with a homebuilt because you dont have a certified
system to confine you. you also dont have the benefits of the
engineering and flight testing that went into sorting out a commercial
design.

more than any other aircraft type a homebuilt's safety rests squarely
on the abilities of the pilot. the upside of that reality is that you
will fly an aircraft you own for more hours and you will be a more
competent pilot as a result.

little things add to survivability. use a lap sash belt or a 5 point
aerobatic harness. dont have switches in the panel area just in front
of you. dont have a sharp edge to the top of the instrument panel.
dont fly the thing if there is a maintenance issue. fix it first.

I have never felt endangered in all the time I've flown mine.
once you get a real aircraft in your hands I'm sure you'll feel just
at ease.
Stealth Pilot

On Fri, 14 May 2004 22:17:24 +0000, Dave S wrote:

In my opinion, the majority of accidents are the result of human error:
Running out of fuel, running into the ground, running into other planes,
flying into instrument conditions without training (and then losing
control) and the like. Certified versus experimental-amatuer built
status has little to do with these human factors.

I feel very human. That's the problem... I currently fly hang-gliders, and
on my first long flight I stalled at about 10M AGL (wind gradient). I bent
the base bar by landing on it, but as luck had it, I was in a harness for
a tandem glider and had a double parachute between my chest and the
aluminium. I think I broke a rib or two anyway, but I'm sure the passive
safety of having a parachute under my chest saved me from more serious
injury.

A friend has the wreck of a homebuilt in his garage. Again, the pilot
stalled at low altitude, but in his case the fuselage broke in half around
the pilot compartment and his injuries were much more serious than mine.

If you are looking for a "volvo in the sky" I cant offer much to you.
Trying to derive a relative safety equation is an apples to oranges
affair unless you can account for hours flown per type, pilot experience
and other factors for which the data isnt routinely sampled and available.

I agree this sounds impossibly fraught. What I would like (ideally) would
be the results of something akin to the car-crash tests that show how the
test-dummies fared in various scenarios - e.g. side impacts etc... I saw a
documentary about car-safety a few years ago, that mentioned that the
technology of crumple-zones and reinforced passenger compartments was
originally developed for WWII naval aircraft. Don't homebuilt designers
think about features such as these? Or would they help in so few scenarios
that it's an irrelevance?

The EAA (www.eaa.org) may be a good source to look at for
charactaristics of certain homebuilts. I seem to remember seeing reviews
of some types of homebuilts in their Sport Aviation publication. They
evaluated things such as static and dynamic stability, control forces,
maneuvering characteristics and the like.

The NTSB (www.ntsb.gov) has accident reports available, and searchable,
for several decades. You can look and see what seems to be the most
common causes of accidents for yourself... by type, by date, by
region...etc.

Thanks, I'll have a browse.

AC

Dave

anonymous coward wrote:
I'd be grateful if anyone can direct me towards links about the relative
safety of different types of homebuilt aircraft. Not figures I can use to
prove to myself that flying a homebuilt is safe, but a discussion of all
the factors that affect safety in homebuilt aircraft. I haven't found much
through google - perhaps it's a contentious subject?

Though I realise that most of the safety equation is down to the pilot,
presumably some types have safer flying characteristics than others? And
presumably crashes in some types are more survivable than crashes in
others in the same way as some car-wreck scenarios that would have been
lethal 20 years ago are easily survivable today?

AC

Landing speeds are a big driver for the amount of injury. I think that the
FAA has a lot of data on this. Can't think of a reference off-hand, but you
can search the NTSB site. But anyway, here's the math: KE = (1/2)mv^2. The
basic conclusion is that accidents occuring at lower landing speeds do less
damage. This was a driver for the design of the RV series aircraft. If you
want safety, get something with STOL capability, make sure there's nothing
in the cockpit that's going to smack you in the back of the head if you
screw up, then practice, practice, practice (with an instructor until you
feel confident).....then practice some more. Avoid low-level aerobatics
until you're a really ****-hot pilot.

You really need to forget about structural protection in a home-built. The
key is to prevent (by flight procedure, pilot skill and knowledge, and by
appropriate vehicle design) accidents from happening in the first place.

Pete
[RV-8A in the planning stages....new shop under construction]

"anonymous coward" wrote in message
news
I agree this sounds impossibly fraught. What I would like (ideally) would
be the results of something akin to the car-crash tests that show how the
test-dummies fared in various scenarios - e.g. side impacts etc... I saw a

I performed a fairly in-depth study of homebuilt accidents towards the end
of last year. The October issue of KITPLANES magazine will include an
article summarizing my results and conclusions.

During my analysis, I looked at the records of individual designs, thought
I didn't include the results in the article. Even though I performed my
analysis on a three-year period, the number of accidents of most particular
types is still fairly low that minor aberrations cause significant changes.

For instance, if there are 2000 examples of type "A" and 200 examples of
type "B", one or two extra crashes will affect the stats for Type "B" a lot
more than Type "A". If 20 Type "A" planes and 2 type "B" planes crash,
they both have the same accident rate. If both have two additional
accidents, Type "B"'s rate will now be almost *double* Type "A"'s. But
does that truly mean that "B" is twice as dangerous as "A"?

We also get into the aircraft type and aircraft operating mode issues. On
my first pass, I found one type of homebuilt with a significantly higher
accident rate than the rest. When I looked closer, I realized that this
was an amphibian...and a lot of the accidents were during water operations.

So I'm reluctant to point fingers are individual aircraft types. Here's a
list of the fleet accident rate (what percentage of a particular type
crashes in an average year) for ten major homebuilt kit companies. Note
that the statistics for companies with multiple types are grouped together
(e.g. the RV series is lumped under one, not listed individually). Only
aircraft listed as being licensed were included...many homebuilts of these
types are on the registration rolls but have the certification type column
blank.

The aircraft included are (in alphabetical order): Avid, Glasair, Glastar,
Kitfox, Lancair, Long EZ, RANS, T-18, Vans, Velocity. Note that this order
does NOT match that of the table below, nor does it include the amphibian
type I mention above.

Annual Accident Rate
% of Fleet
A 1.3%
B 1.2%
C 1.8%
D 4.9%
E 0.9%
F 1.0%
G 0.7%
H 2.4%
I 1.9%
J 2.9%


Ron Wanttaja

SNIP
I agree this sounds impossibly fraught. What I would like (ideally) would
be the results of something akin to the car-crash tests that show how the
test-dummies fared in various scenarios - e.g. side impacts etc... I saw a
documentary about car-safety a few years ago, that mentioned that the
technology of crumple-zones and reinforced passenger compartments was
originally developed for WWII naval aircraft. Don't homebuilt designers
think about features such as these? Or would they help in so few scenarios
that it's an irrelevance?



Again, I have read (but dont have the source handy) that one of the
biggest determinants of lethality in a small aircraft accident is based
on wether the aircraft contacts the ground in a near-level, controlled
attitude (or not). Crumple zones and side-impact airbags wont do much
when you hit upside down, in a spin, or screaming out of the sky with a
yard dart's downward trajectory. Preventing departure from controlled
flight is the key to survival. That is why you 1) ALWAYS fly the plane
first and 2) NEVER give up.

Dave

On Sat, 15 May 2004 15:14:41 +0000, Pete Schaefer wrote:

Landing speeds are a big driver for the amount of injury. I think that the
FAA has a lot of data on this. Can't think of a reference off-hand, but you
can search the NTSB site. But anyway, here's the math: KE = (1/2)mv^2. The
basic conclusion is that accidents occuring at lower landing speeds do less
damage. This was a driver for the design of the RV series aircraft. If you
want safety, get something with STOL capability, make sure there's nothing
in the cockpit that's going to smack you in the back of the head if you
screw up, then practice, practice, practice (with an instructor until you
feel confident).....then practice some more. Avoid low-level aerobatics
until you're a really ****-hot pilot.

I like the look of the IBIS (http://www.junqua-aircraft.com/) and I'd
prefer to build in wood. But the more I read, the less good an idea the
Ibis seems (fast landing speeds - only a few complete, so perhaps more
prone to 'bugs' than established designs such as the LongEZ and friends).

I feel more and more drawn towards the idea of building a wooden 3-axis
microlight - some of them seem to have quite short build times, and as you
say, slow landing speeds have got to be a good thing.

You really need to forget about structural protection in a home-built. The
key is to prevent (by flight procedure, pilot skill and knowledge, and by
appropriate vehicle design) accidents from happening in the first place.

I hope I don't seem paranoid, but assuming I'm likely to be flying for 50
years, even accident rates down in the low percents seem quite alarming.

Always grateful for advice,

AC


Pete
[RV-8A in the planning stages....new shop under construction]

"anonymous coward" wrote in message
news
I agree this sounds impossibly fraught. What I would like (ideally) would
be the results of something akin to the car-crash tests that show how the
test-dummies fared in various scenarios - e.g. side impacts etc... I saw a

On Sat, 15 May 2004 19:34:27 +0000, Ron Wanttaja wrote:

I performed a fairly in-depth study of homebuilt accidents towards the end
of last year. The October issue of KITPLANES magazine will include an
article summarizing my results and conclusions.

Thanks, I'll look forward to the article.

AC