Air safety: When statistics are used to kill the messenger

Long time ago, I observed that big and long-range planes -with a few exceptions- always had a safety record better than the one more little planes had. Many explanations were given to this fact: Biggest planes get the most experienced crews, big planes are more carefully crafted… it was easier than that: The most dangerous phases in flight are on ground or near to the ground. Once the plane is at cruise level, the risk is far lower. Of course, biggest planes make long flights or, in other terms, every 10 flown hours a big plane could perform, as an average, one landing while a little one could land 10 times. In a statistical report based in flown hours…which one is them is going to appear as safer? Of course, the big one. If statistics are not carefully read, someone would started to be worried about the high accidentability rate of little planes, if compared with the big ones.

Now, the American NTSB has discovered that helicopters are dangerous: http://www.flightglobal.com/news/articles/ntsb-adds-helicopters-ga-weather-to-quotmost-wantedquot-394947/  and the explanation could be similar, especially if they address the HEMS activity: Emergency medical services are given an extremely short answering time. That means flying with machines that can be cold at the moment of performing an exigent take-off, for instance, very near to a hospital or populated places where they need to make an almost vertical take-off. Once they are airborne, they need to prepare a landing near to an accident place. The place can have buildings, unmarked electrical wires and, of course, it can be from fully flat at sea level to a high mountain place. Is the helicopter risky or the risk is in the operation?

Of course, precisely because the operation is risky, everything has to be as careful as possible but making statistical comparisons with other operations is not the right approach. Analyze in which phase of the flight accidents happen; if the pilot does not have full freedom to choose the place to land, at least, choose an adequate place for the base. Some accidents happened while doctor onboard was seeing that they were very near to an electrical wire and assumed that the pilot had seen it…all the eyes are welcome, even the non-specialized ones. Other times, non-specialized people asked and pressed for landing in crazy places or rostering and missions are prepared ignoring experience and fatigue issues. That is, there is a lot of work to do in this field but, please, do not use statistical reports to justify that by comparing things that are really hard to compare.

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