RON WANTTAJA
BETTER PILOT / SAFETY WIRE
Cause & Effect
The Causes of Homebuilt Accidents
LET’S CUT RIGHT TO THE CHASE…what are the main causes of homebuilt
aircraft accidents? I downloaded National Transportation Safety Board
(NTSB) accident reports for the years 1998 through 2007 and categorized the
the cause of each of more than 2, 100 “homebuilt” accidents. It shouldn’t be a
surprise to find that failure of stick-and-rudder skills (pilot mishandling/
error) was the leading single cause of homebuilt accidents. These accidents
consist basically of ground loops, undershoots, overshoots, and stalls.
The second-place category is a bit unsettling: undetermined engine failure. These are accidents where the engine quit, but the N TSB was unable,
afterward, to determine why. It could have been carburetor icing; it could
have been vapor lock in the fuel lines or even a pilot who accidentally turned
the fuel off and didn’t admit it. These undetermined failures caused more
than 9 percent of homebuilt accidents. In fact, about one-third of all homebuilt accidents start with an engine failure, be it “undetermined,” internal
failure, or problems with the fuel system. Sadly,
about 10 percent of all homebuilt accidents can be
attributed to either a mistake made by the builder
or a mistake by the person performing the maintenance on the aircraft. If one includes cases
where a wrench-turner’s actions contributed to
the accident but didn’t directly cause it, the percentage jumps to 14 percent.
That means one in seven homebuilt accidents
involved builder or maintainer error. Something to
think about when we’re working on our aircraft.
Ron Wanttaja, EAA 275698, built and flies a Fly Baby and
has long studied homebuilt accident statistics.
Homebult
Aircraft
Accident
Causes
Human Error
(Pilot) 51%
(Builder) 10%
Mechanical Error
28%
Other
11%
39% General Pilot Error
5% Fuel Exhaustion or Starvation
4% Unnecessary Low Altitude
2% Inadequate Preflight
1% IFR to VFR Transition
6% Mfg. or Construction Error
4% Maintenance Error
9% Undetermined Power Loss
7% Engine Mechanical
6% Other Mechanical
4% Fuel System
2% Carburetor Ice
11% Wake Turbulence, CG/Wgt,
Mid-Airs, etc.
