half of homebuilt accidents involve conven-tional-gear aircraft.
Maneuvering at Low Altitude: This includes traditional “buzzing,” as well as low
passes and pull-ups over the runway or flying up the wrong mountain canyons. These
events have a high mortality rate.
Pilot Error/Bad Flare or Bounce: That last
couple of feet or so to the pavement is critical, and can be where lack of experience or
attention comes back to bite.
Maintainer Error: Mistakes induced during
maintenance of the aircraft. About 60 percent
of the cases involve purchased airplanes, maintained either by the new owner or an A&P.
Mechanical Failure of the Landing Gear/
Brakes: Few components on an aircraft
take the regular pounding that the landing gear gets, and a failure often results in
an impromptu tour of the airport environs,
potentially at an odd attitude. Fortunately,
injuries are rare (no cases of fatalities or
serious injuries in our five-year period).
Fuel Exhaustion: Plain ol’ running
out of gas.
Carburetor Ice: These cases involve
both the pilot’s failure to properly use carb
heat and those where the airplane is not
equipped with carburetor heat.
Fuel Starvation: Having fuel, but not
feeding it to the engine properly.
As far as fatal accidents are concerned,
No. 1 is pilot error/stalls. Maneuvering at
low altitude comes in at No. 2, and undetermined engine failure is No. 3.
More than half of all homebuilt accidents
are caused by pilot error, though 2012 was
an improvement in this regard.
However, note the “dirty dozen” results.
When the statistics were examined with a
finer comb, the single most-common cause
of homebuilt accidents was the unexplained
loss of engine power. It accounted for 9
percent of all crashes in the past five years.
Remember, though, that’s just the
unexplained engine failures. When we add in the
explainable ones, we find that 31 percent
of all E-AB accidents start with the loss of
power. It may be due to an engine mechanical issue, it may stem from the pilot using
up all the fuel, or blame may lie with the
builder’s or mechanic’s workmanship. But
nearly a third of our accidents begin with
engine power suddenly not being available.
As builders, pilots, and maintainers of
homebuilt aircraft, we need to work on the
reliability of our engines and related systems. But we also need to be more prepared
for when it does happen. If your Lycoming
throws a connecting rod, if a piston on your
Cuyuna seizes, or the belt on your PSRU
shreds, you need to be ready. An undamaged
homebuilt sitting in a pasture is a better testament to your skills than a fancy paint job.
Ron Wanttaja, EAA 275698, is the author of two
aviation books, Kit Airplane Construction and Airplane
Ownership, as well as two young-adult historical novels
and numerous magazine articles. He owns a 1982 Bowers
Fly Baby and maintains a web page for devotees of the
design at www.BowersFlyBaby.com.
Basic source of the data for this report is the downloadable
NTSB accident databases. The accidents flagged by the NTSB
as “homebuilt” are cross-referenced with the FAA registration database to determine the actual certification status of
the aircraft. Those licensed in other than E-AB are eliminated, as are unregistered or foreign-registered aircraft.
About a quarter of the entries do not have a certification
entry in the FAA database. For these, the aircraft make
and model are examined to see if the aircraft is a type
that is not typically certificated as amateur-built. If so, it
Finally, the “purpose of flight” entry in the accident
database is used to weed out air show, racing, and other
uses not typical of personal E-AB operations. Because of
this, my totals may not exactly match the official tally.
It should be understood that not every case of bent
metal (or splintered wood, or crushed composite) ends
up in the NTSB accident records. If serious or fatal injuries didn’t occur, the damage isn’t substantial, or the
other criteria in 49 CFR Part 830 are not met, the event
is considered an “incident” and is not included in the
NTSB’s accident tally.
Also, unlike most GA pilots, homebuilders are usually
capable of disassembling and transporting their aircraft.
“Substantial damage” or no, some damaged homebuilts
end up hidden in garages and hangars with the NTSB
none the wiser.
After the E-AB aircraft have been identified, the NTSB
data is examined to determine the cause of the accident. The NTSB narrative report is used to determine the
first major event (the “initiator”) of each accident. This
conclusion may differ from the NTSB’s final “probable
cause” ruling. For example, if the engine fails and the
pilot stalls during an attempted forced landing, the NTSB
probable cause will be pilot error. As amateur-built aircraft have a greater tendency toward mechanical issues,
tracking the initiators rather than NTSB probable cause
results in better understanding of hardware problems.
The initiators are tracked in 51 separate categories. Where
more than one factor is involved, these subsidiary factors
are also recorded.
The accidents are maintained in a database
currently covering 15 years (1998 to 2012, inclusive).
UNDERTERMINED ENGINE FAILURE
PILOT ERROR / WINDS
PILOT ERROR / STALL
PILOT ERROR / LOSS OF DIRECTIONAL CONTROL ON LANDING
MANEUVERING AT LOW ALTITUDE
PILOT ERROR / BAD FLARE OR BOUNCE
MECHANICAL FAILURE—GEAR / BRAKES