Crashing By The NumbersImproving safety means improving the odds with an understanding of human behavior
Every pilot makes mistakes. On an large scale they happen at surprisingly predictable rates with different errors happening at different rates. Managers and designers who fail 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 be maximized through accountability (such as performance monitoring), culture and empowering fellow pilots to work as teams, fostering a willingness to speak up.
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 never want to fail, but they get complacent. 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.
Any airline manager that responds to a safety or procedural suggestion with:
"We can't make a procedure for everything" or
"At some points we have to let pilots be pilots."
Has, in fact, abrogated his duty. While both statements are completely true it denies the responsibility for them to make procedures that address the largest risks.
Flaps Up Takeoff
Note: the numbers used here are estimates used to show a point.
With no good procedure in place, a pilot will forget to set the flaps around one of out 500 times. A good procedure with crew coordination reduces that to maybe one out of 3000 times. We can also calculate that, on one out of 10 takeoffs, leaving the flaps up for takeoff on a modern transport jet will result in a fatal accident. 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. The same catastrophe got Spanair Flight 5022 taking off from Barcelona El Prat Airport. Both of them missed the flaps during their checklist reading and the takeoff configuration horn never sounded.
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 mentioned above.
Before GPWS came into being, The chances of a CFIT accident were about 1 in 2,000,000 flights. Now with the most enhanced version mandated in U.S. airlines, the odds are about 1 in 20,000,000. 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.
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.
Â© 2016 Jeff Goin & Tim Kaiser Remember: If there's air there, it should be flown in!