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Single-Seat Accident Records (Was BD-5B)



 
 
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Old November 15th 03, 09:44 PM
Ron Wanttaja
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Default Single-Seat Accident Records (Was BD-5B)

With the current discussion in another thread regarding the accident record
of the BD-5, I thought it might be interesting to do a little more in-depth
look. I decided to examine the accidents between 1 January 1990 and 13
November 2003 and do a breakdown as to relative accident/fatality rate,
pilot experience, and cause of accidents.

To give a little depth to the situation, I also ran the same analysis for
two other single-seat homebuilts. I selected the RV-3 as an airplane with
a similar "mission" as the BD-5. And I use the Fly Baby because, well, I
ALREADY had the downloaded NTSB files on it. :-)

DATA SOURCE:

I downloaded the accident reports from the NTSB web pages for these three
aircraft. In all cases, I used several variants of the names to try to
avoid missing any reports.

I also ran a simple search for all amateur-built accidents and
amateur-built accidents with fatalities over the same period.

I do not have any data indicating how many of each type of aircraft existed
in each year. Therefore, I used the number of each type registered in
January 2003 for the basis for some of the percentages. I used the FAA/EAA
practice of only counting those airplanes which are listed as having
airworthiness certificates, even though the listings are somewhat
inaccurate. Thus, the following fleet-size figures are used:

Fly Baby: 265
BD-5: 81
RV-3: 170

Using the January 2003 fleet size numbers is only for comparison; remember,
it does not reflect the number of a given aircraft in the fleet at the time
of any particular accident.

When running percentages based on this fleet size, I did *not* add back the
crashed airplanes into the total fleet size. This is different from my
earlier, BD-5-only report, so the percentages will be slightly different.

ANALYSIS METHOD:

Using the NTSB reports, I extracted key features and transferred them to a
database. The database included items like the type of aircraft, date of
accidents, number of fatalities and injuries, the ratings held by the
pilot, whether the aircraft was on its first flight, a "test flight", or
whether the pilot had newly purchased the plane, and 36 separate categories
for the accident cause.

I would enter the NTSB primary cause as a "1" in each category, and any
related events as "2"s. However, when developing the cause statistics, I
ignored the primary/secondary indications and just counted whether the
categorized item was a factor.

I did vary from the NTSB cause determination in one kind of case: When an
accident occurred after a loss of power. Often, the NTSB assigns pilot
error as a cause (either primary or contributing) if the pilot in not able
to safely land the aircraft after an engine failure. In my analysis, I
considered only the even that *caused* the emergency; if the pilot
misjudged a deadstick landing approach, I did not flag that as an accident
cause.

Keep in mind that the statistical base is NOT high for any of these three
aircraft. We're talking 15-20 accidents over a 13-year period, here. But
things are easier to compare when presented in percentages.

Finally, the data presented may appear better if you switch your newsreader
to a fixed-spacing font rather than variable spacing.

OK, on to the results!

OVERALL ACCIDENTS:

Here are the total number of accidents I extracted from the NTSB online
database. Again, this is the period from 1 Jan 1990 to 13 November 2003.

Type Accidents fatal
All Homebuilts 2881 837
Fly Baby 15 5
BD-5 22 9
RV-3 14 5

OVERALL ACCIDENT RATE:

Let's look at the overall accident rate for the homebuilt fleet and the
individual types. The "Accidents" is the total number of accidents vs. the
number of that type on the Jan 2003 register, and the "Fatals" column is
the number of accidents in which the pilot was killed.

Accidents Fatals
All Homebuilts 11.1% 3.2%
Fly Baby 5.7% 1.9%
BD-5 27.2% 11.1%
RV-3 8.2% 2.9%

FATAL ACCIDENTS TO TOTAL ACCIDENTS

These ratios show the relative number of fatal accidents vs. the total
accidents for that type.

Type Fatal Rate
All Homebuilts 29.1%
Fly Baby 33.3%
BD-5 40.9%
RV-3 35.7%

The number of accidents involving fatalities is one indicator of the
relative crash-worthiness of a design. However, these factors do not
reflect the type of accident...a structural failure at altitude is
generally not survivable, no matter the design of the aircraft.

PILOT QUALIFICATIONS

The NTSB reports, especially the older ones, did not always list the
ratings held by the accident pilot. Less than half the reports contained
the pilot rating information. For the purposes of this analysis, I have
presumed that the pilots whose qualifications were not listed had Private
licenses.

Private Comm ATP
Fly Baby 80.0% 13.3% 0.0% (One unlicensed pilot)
BD-5 63.6% 18.2% 18.2%
RV-3 71.4% 21.4% 7.1%

Again, keep in mind the small sample size here. The 7.1% for ATPs involved
in RV-3 crashes represents *one* individual.

AIRCRAFT TEST STATUS

Occasionally, the NTSB reports indicate that the airplane was on its first
flight, or was newly-purchased. Or, they may indicate that the airplane
was on a "test flight." It is unknown whether other accidents actually
occurred during these phases; the NTSB investigator may not have been aware
of it or didn't consider that it was a significant contributor to the cause
of the accident.

"First flight": Aircraft specifically identified as never having flown
before.

"Test Phase": Aircraft identified as still in its FAA-specified test
phase, or the NTSB report indicates the purpose was a test flight.

"New Pilot": NTSB report says the owner had recently purchased the
aircraft.

First Flight Test Period New Pilot
Fly Baby 0.0% 0.0% 13.3%
BD-5 9.1% 22.7% 9.1%
RV-3 0.0% 0.0% 21.4%

For the Fly Baby, a single accident was 6.7% of the total, the BD-4 was
about 4.5%, and the RV-3 was about 7.1%.

ACCIDENT CAUSES

As mentioned earlier, I include both the primary and any secondary causes
in this list, with the exception of any pilot error occurring after a loss
of power.

The accident categories I use a

"LOP - Non-Pilot": A loss of power that is not attributable to the pilot's
actions. This could include blockage of a fuel line, magneto failure, etc.
This category is also used for unexplained losses of power.
"LOP - Pilot": A loss of power attributable to pilot actions...fuel
exhaustion, carb ice, etc.
"Pilot Judgement/ mishandling": The classic "Pilot Error" category. These
factors include both cases of bad decision-making as well as those of
losing control of the aircraft due to windy conditions. Keep in mind that
this really isn't the only "pilot error" category..."LOP - Pilot," "Density
altitude,", "Maneuvering at Low Altitude," etc. are cataloged individually
and are NOT reflected here.
"VFR to IFR": Basically, scud running.
"Mechanical Failure - Airframe": Generally, structural failure of some
sort, though not necessarily of critical structure. Includes door, canopy,
panel, etc. failures.
"Mechanical Failure - other": Generally failures of non-engine or fuel
system accessories. Does include propeller and spinner failures.
"Maneuvering Low Alt": Unnecessary low flying. Does not include cases of
high-altitude flying where the terrain outclimbs the airplane.
"Density Altitude": Hot/High conditions
"Builder error:" Workmanship problems, deviation from instructions, etc.
"Mechanical Failure - Maintenance": Failures due to mistakes while
performing maintenance...leaving bolts out, etc.
"Midair": Collision with another aircraft.
"Inadequate Preflight": Failure to detect flawed conditions or plan the
flight properly.
"Inexperience": Lack of experience, either in total time or in the
accident airplane.
"Fire": Pre-crash fires.
"Undetermined": No surviving witnesses and the wreckage is too damaged to
show any potential mechanical flaws.

Again, keep in mind that both primary and secondary causes are included
here, so the columns won't add up to 100%.

(FB is Fly Baby)

FB BD-5 RV-3
LOP - Non-Pilot 20.0% 40.9% 14.3%
LOP - Pilot 13.3% 0.0% 14.3%
Pilot Judgment/ mishandling 13.3% 36.4% 28.6%
VFR to IFR 6.7% 0.0% 7.1%
Mechanical Failure - Airframe 13.3% 0.0% 21.4%
Mechanical Failure - other 0.0% 0.0% 14.3%
Maneuvering Low Alt 0.0% 0.0% 7.1%
Density Altitude 0.0% 4.5% 0.0%
Builder error 13.3% 4.5% 0.0%
Mechanical Failure - Maint. 20.0% 9.1% 7.1%
Midair 0.0% 0.0% 7.1%
Inadequate Preflight 6.7% 0.0% 0.0%
Inexperience 6.7% 18.2% 7.1%
Fire 0.0% 0.0% 7.1%
Undetermined 6.7% 0.0% 0.0%

Percentage one accident
represents: 6.7% 4.5% 7.1%

The BD-5 has a loss of power accident rate twice that of the Fly Baby and
almost three times of the RV-3, reflecting the design's long problems with
finding a reliable powerplant. The Pilot Judgment/Mishandling categories
are fairly close for the RV-3 and BD-5, but the BD-5 has trigear and the
RV-3 is a taildragger. The Fly Baby, though, is half their rates, which
probably reflects the BD-5/RV-3 high-performance status. The BD-5's
"Inexperience" results are interesting, too.

Anyway, that's what the statistics look like.

Ron Wanttaja
 




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