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Every pilot makes mistakes. And on an large scale, they happen at a
surprisingly predictable rate. Every procedure gets done improperly
or skipped at some
rate. Managers and designers
who are unwilling to recognize
this fact pass up opportunities for real safety improvements.
A good procedure gets the job done while being error
tolerant, especially for interruptions.
Compliance must also be maximized through accountability (such as
performance monitoring), culture and empowering fellow pilots who work
in teams. Our greatest success comes by working with the human operators in a
realistic manner. The statement "we have to have the
pilots be pilots" is a cop out. Pilots don't want to fail. Real accident rate reduction is a combination of reducing the error
rate and
reducing the impact of any single error (error tolerance). Here are some
examples.
Flaps Up Takeoff
With no good procedure in place, a pilot will forget to set the flaps
approximately one of out 500 times. A good procedure with crew
coordination reduces that to
maybe one out of 3000 times. In one out of 10 takeoffs, leaving the flaps
up for takeoff on a modern transport jet will result in a crash (shortish runways, heavy weights
or combinations thereof). So, with a good procedure in
place, the chances of crashing due to improper flap setting is 1 in
30,000. With over 20,000 flights per day in the U.S. we would
expect an accident about once every 1.5 days from improperly set
flaps.
That's obviously not acceptable so a solution was developed: the
takeoff configuration warning. It beeps if any critical control is not set
when the throttles are advanced for takeoff. Being mechanical, it's pretty
reliable (more than the humans, I'm afraid) plus it gets tested before
every takeoff (a procedure that started after the crash mentioned below).
Its reliability is such that it will be inoperative on about one in 50,000
flights. That lowers the odds of a no-flaps crash to one in 1.5 billion.
Good but not foolproof either, as this Northwest
DC-9 crew found in Detroit. They missed the flaps during their checklist
reading and the takeoff configuration horn never sounded.
CFIT
Controlled flight into terrain
has long been a major cause of fatal airline accidents. Technology has
improved enough to make it possible for the airplane to "know" where it is
and where the terrain is. That has been combined with a warning that
verbally prompts the pilot to "pull up" when rising terrain
threatens. This Enhanced Ground Proximity Warning System (EGPWS) has proven
enormously successful, much like the takeoff warning horn.
Before GPWS came into being, The chances of a CFIT accident were
about 1 in 200,000 flights. Now with the most enhanced version mandated in U.S.
airlines, the odds are about 1 in 2,000,000. Sadly, the most likely cause
of a CFIT accident is now the pilot ignoring warnings from his
aircraft and running into the terrain anyway.
Indeed, flight data recorders have found exactly this happening with aircraft
getting within hundreds of feet of a crash—a statistic that points to the need for
even better training with appropriate emphasis on
compliance. Any pilot that's willing to ignore such warnings should
be shown the door to a safer occupation.
Odds
We can do a lot to stack these odds in our favor and
that effort
continues. Sometimes simple solutions go unused
for many reasons. Pride, cost, and laziness are just a few that we are all
subject to as humans. We as pilots, management and the traveling public can help by
encouraging the practices that will continue to make our air
transportation system the best it can be. |
Our
procedures, equipment and materials should accept human limitations and
work to reduce their effects. Airlines have done an amazing job with this
effort already but much more can be done. Cheaply, too. The ideas
presented here could help. |
