Saturday, December 29, 2012

Fatality Statistics Meaningless as Safety Measure

As certain as the ball will drop in New York's Times Square on Monday midnight, there will be a round of news stories summing up 2012 in terms of aviation safety. Oh wait a minute, it's already started. 

"Overall, it was certainly the safest year ever," Paul Hayes told UPI.com. Hayes is the director of safety at Ascend, a consulting firm, that specializes in the commercial and financial aspects of aviation. 

I've got no problem with good news, or with the numbers that Hayes and Ascend present. The problem is the meaninglessness of the particular criteria used. Ascend is restricting its safety data to accidents with fatalities.  

In the vast majority of aviation accidents, nobody dies. When the National Transportation Safety Board did an in depth statistical study 10 years ago, the survival rate in reportable accidents was 95%.  If that surprises most people, and I suspect it does, Arnold Barnett, a professor of statistics at the Massachsetts Institute of Technology can explain why. "The events that make the greatest impression are the ones that involve fatalities," he said. 

The disconnect between perception and reality - (which has as its spokesman, Ryanair boss, Michael O'Leary) may be confusion over the term, “accident”. 

To the general public, airplane accident brings to mind the scene from Denzel Washington's new movie Flight, in which a plane smashes to earth trailing tongues of fire.  But an accident is also an aborted takeoff and a runway overrun, an in-flight upset and a structural failure. Turbulence and plane to plane collisions are also accidents and while people can be injured seriously, all this mayhem is not in the statistics Ascend is feeding to reporters as it raves enthusiastically about the safest year ever in aviation. 

When safety is measured by an absence of fatalities, the significance of non lethal events is diminished even though most safety specialists think these percursors are the most indicative of an overall safety culture. A preventive approach to reducing risk is so important commercial operators in most parts of the world are required to have safety management systems

Several years ago, at the International Society of Air Safety Investigators annual seminar, the entire three day program was dedicated not to presentations on the big accident investigations, but on how to better probe the little ones.  "Our biggest opportunity to make things better is before someone dies," one participant told me.

Robert Sumwalt, a member of the NTSB is fond of telling people that culture of safety, is one where people do the right thing - the safe thing - even when no one else is watching. That's not the spectacular crash, everybody is has an eye on that. 

Nope, it's a loose row of airliner seats and the ruptured fuselage at thirty-four thousand feet.  It's the engine failure on an Airbus A380 and the flight attendant's severed finger. When we see a reduction in these events we really will have something to celebrate.





Post a Comment