Bad statistics on CNN (surprise)
I’m watching this program on CNN called “No Survivors: It Could Happen Again.” The show is about TWA Flight 800, the 747 traveling from New York to Paris that blew up in July 1996 of a fuel tank explosion. They’re interviewing some big shot at NTSB or something and he says that, looking at the records, they see one fuel tank explosion on average every 4.5 years, as a way of demonstrating how bad of aircraft manufacturers have been at keeping ignition sources out of fuel tanks in airplanes. The interviewer, being very “helpful”, notes that it’s been 4 years and 8 months since the last explosion, and asks the question, “Are we overdue?”
And this NTSB guy, who is obviously a wizard at mechanical engineering and other stuff based on the other stuff he’s said in the show, says, “Yes.” Argh! How can someone so smart in one field be so ignorant of another related field, statistics? The correct answer is, no, we are not “overdue” in any sense of the word. Random events happen with a certain frequency, and an average time between events can be calculated. But that average time has no bearing whatsoever on when the next occurrence will happen. The odds of another fuel tank explosion happening today are the same whether one just happened yesterday or one just happened a decade ago.
All things considered, about two fuel tank explosions per decade in commercial airliners really isn’t that bad. The show talks about a nitrogen system that floods out the air in fuel tanks and make explosions actually impossible, but it isn’t being used on civilian aircraft due to expense and weight (the Air Force does use it in a lot of their planes).
