From Australia comes a story of a potential airliner crash caused by a wasps’ nest. The plane had flown in from Singapore and was headed back on the return trip. It was on the ground for two hours. The first takeoff attempt had to be scrubbed because of an instrument problem. As soon as the pilot took off on the second attempt, he radioed the tower that he needed to make an emergency landing because he had no way to measure his airspeed to know if he was going fast enough to stay in the air.
Investigators traced the problem to a wasps’ hive that had formed in a piece of equipment known as a Pilot Probe. Their report concludes that the wasps had built the hive in the two hours that the plane was on the ground.
What’s the lesson here? Always recognize the potential for the unpredictable to occur. One of the newer tools to take hold in the safety profession is “barrier management.” It involves identifying potential hazards and focusing on the barriers that can be implemented to protect workers and sites from those hazards. It is a valuable tool, especially because it can be quantified (“we have established 20 barriers on this operation.”) and because it ties together a lot of different safety measures into a coherent system (training, procedures, reviews, etc.).
The problem with barriers is that, when we try to make order out of what is essentially a chaotic world, we tend to convince ourselves that the world fits our orderly model. Being able to identify known hazards and to institute protections against those hazards is a very valuable thing and that is why the barrier approach is worth doing. But some part of us needs to always be wary of the unexpected event that is so random in nature that it will never show up in our carefully plotted barrier diagram. There is an old Yiddish say, “Man plans and God laughs.” A similar Scottish saying is “the best laid plans of mice and men often go awry.”
Hazard analysis and barrier plans are important, but the lesson of the wasp in the airplane is that we always need to be on the lookout for the hazard we could never anticipate.
Thanks to Dennis Bryant for pointing this out on his blog.