Critique of: Crash Risk in General Aviation

On Sat, 14 Apr 2007 01:05:35 -0000, Jim Logajan
wrote in :

For what it is worth, my feedback on your proposed response:

Larry Dighera wrote:
For pilots without instrument training, flying from visual flight
rules into instrument meteorological conditions is a perilous
scenario.

[There are a miniscule number of airmen who hold FAA certificates,
that have not received any instrument training; instrument training is
not required to obtain a Glider certificate. The phrase the
researchers probably meant to use was 'instrument rating' not
'instrument training.'

Regardless, it is true that the average life expectancy of a pilot who
is not instrument rated and qualified (recent experience) is a bit
over a minute when unintentionally finding himself in a cloud that
totally obscures his outside reference.]

I think a more appropriate rebuttal here is that other sources, such as
the annual Nall Report, find that in 2005 weather related accidents
accounted for only about 11% of all fatal GA accidents. By comparison,
Nall claims 27% of fatal GA accidents in 2005 are due to pilot control
errors during what it calls "maneuvering flight." Therefore the emphasis
on VFR into VMC and lack of mention of "maneuvering flight" by the
researchers as a causal factor is an improper inversion of priorities.

Thank you for your insight and the source reference. I'll add your
point to my critique.

What is your feeling about my disclosing the hazard statistic for VFR
into IMC for un-rated/not-current pilots?


In 1990, the FAA amended regulations regarding background checks
on pilots for alcohol-related motor vehicle convictions, requiring
pilots to provide a written report of each alcohol-related traffic
offense within 60 days of the conviction. Flying privileges can be
suspended or revoked if a pilot has had 2 or more convictions for
driving under the influence in the past 3 years. A recent cohort
study indicated that a history of driving while intoxicated is a
valid risk marker for general aviation pilots. After adjusting for
age, sex, and flight experience, the study showed that a history
of driving while intoxicated was associated with a 43% increased
risk of aviation crash involvement.12 Following intensive research
and interventions, the proportion of alcohol involvement in fatal
general aviation crashes has decreased progressively from more
than 30% in the early 1960s to about 8% today.13

I think a rebuttal may be approprihere might be:
[The 2006 Nall Report found that alcohol and drugs account for only about
1.1% of all accidents in the past few years. This is again an inversion
of causal priorities and places an improper emphasis on a minor causative
factor. Further efforts and analysis on reducing alcohol and drug related
aviation accidents is misguided effort that is better spent elsewhere.]


Another good point. Thank you.

[A pilot who flies without the use of shoulder restraint belts is a
fool.

It is curious that the researchers failed to mention ballistic
parachute recovery systems like those currently mandated for the
recently FAA certified Cirrus aircraft.]

I don't think you can properly claim the FAA mandated the Cirrus BRS.


You may be correct. It is my understanding that Cirrus chose the BRS
to comply with spin recovery certification. I suppose that was
Cirrus's choice of an alternate compliance method, not an FAA mandate.
I'll try to rephrase it.


The general aviation crash fatality rate has remained at about 19%
for the past 20 years while the overall airline crash fatality
rate has declined from 16% from 1986 through 1995 to 6% from 1996
through 2005.4,24

[Due to the reduction in airline operations due to the September 11,
2001 terrorist attacks, increased airport security, and general
decline in airline ticket sales, that statistic may be misleading.]

Their statistics look okay to me, though I'm not sure where they get the
6%. From their two NTSB references, out of 34 accidents listed for CFR
121 carriers, 3 had fatalities (~9%) and out of 1669 GA accidents, 321
had fatalities (~19%). Averaging over the last several N years may yield
~6%. Maybe they did that.

The point I was attempting to make, was that during the sample period
cited airline travel was diminished by the 9/11 influence, and that as
a result, it is reasonable to expect the number of airline fatalities
to be less than it was during a period of higher airline travel rates.
Am I mission your point?


The higher fatality rate for general aviation crashes may be
because such aircraft are not as able to withstand impact forces
and protect occupants from death and severe injury as commercial
aircraft are.

[A more robust airframe requires increased weight. There is a
tradeoff of safety for performance.]

Another objection would be that the difference in rates may be due to the
nature of the accidents the two classes of flights encounter. Having two
experienced pilots on board would almost certainly skew where and when
accidents take place such that the impacts on the airframes are not
comparable.


True.


In recent decades, while major airlines have improved seat
strength, revised exit row configurations, and used more fire
retardant materials, few improvements have been made in general
aviation aircraft, in part, because federal regulations only
require safety improvements for entirely new aircraft models. A
corresponding policy for automobiles would have meant that
Volkswagen Beetles could have been sold without seatbelts for
decades after federal regulation required them in all new cars.

[The Volkswagen analogy is flawed. The ubiquitous Cessna 172 aircraft
have had should restraints for decades despite their first being FAA
certified in the 1950s.]

Typo: "shoulder restraints" not "should restraints".


Thank you. I'm sure there are others too.

To improve the safety of general aviation, interventions are
needed to improve fuel system integrity and restraint systems,
enhance general crashworthiness of small aircraft,

Those are only viable measures if their added weight and cost do not
so negatively impact aircraft performance and affordability so as to
render General Aviation operations impractical.]

Furthermore, restraints systems in many small aircraft are already
superior to those found on airlines.

Ummm. I don't recall seeing any shoulder restraints on airline
seating.

Thank you for your input. It really helps to have other points of
view.