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The Pareto Principle

The vital few and the useful many.”


August 10, 2012
By Walter Heneghan

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The vital few and the useful many.”

This is the academic shorthand for a widely known and commonly used distribution known as the Pareto Principle: the 80-20 rule – 80 per cent of our time is taken up doing 20 per cent of our work.

That is a simplistic view of this rule, and there are many exceptions, but the principle has been shown to be relatively valid in a wide variety of circumstances: wealth distribution (the richest 20 per cent own 80 per cent of all wealth); some businesses (80 per cent of a company’s revenues comes from 20 per cent of its clients); or the service industries (it may mean that 80 per cent of the work gets done by 20 per cent of the employees).

I don’t wish to delve too deeply into the math of this “rule,” so I will leave that to the “Googlers©” among us. I thought, however, that it might be instructive to see if or how this rule applied to the Canadian helicopter industry and its accident dataset. Having been spurred into further analysis through a conversation with several TSB investigators, I completed a brief analysis of the Civil Aviation Daily Occurrence Reporting System (CADORS) database and have come up with some interesting facts. I know that this data does not provide a total picture due to varying reporting requirements – aircraft type, class and weight, etc. However, the database shows that since 2007 there have been 195 reported accidents involving helicopters with an astounding 116 persons injured and 75 fatalities. Let that sink in: 75 people have died in helicopter accidents in Canada since 2007, an average of 15 per year.

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This number really rattled me as I continued to review the available information to see if I could identify the “vital few” cause factors. I found that the distribution was, in fact, close:  27 per cent of the accident categories accounted for 80 per cent of the total number of accident events and that 80 per cent of the fatalities came from 28 per cent of the events. So, it would stand to reason that if we know what those categories are then we can take the first big step towards creating better risk- and hazard-management strategies to address these areas of concern.

The top accident categories, as defined by the TSB are controlled flight into terrain (CFIT), rotor strike, roll over, and loss of control – in-flight, engine failure, hard landing and loss of power. The top fatality categories are CFIT, Engine failure, Loss of Control and Loss of Power. So, we now have a very clear risk profile: CFIT, engine failure/power loss and loss of control events are the categories that cause the most accidents and the most fatalities. I wrote about CFIT and some ideas in managing that risk in an earlier column, so now let’s talk about engine failures and power loss events.

I used to subscribe to the theory that the engines in today’s aircraft are virtually bulletproof – that they are among the most reliable components on the aircraft and that they rarely fail. I was surprised to learn that there have been 29 reported engine failure and power loss events reported since 2007. This means there should be no fewer than six engine failures in the industry each year. This number does not account for chip lights that indicate a forced landing, engines that seize on shutdown or a wide myriad of other potentially catastrophic events.

How do we mitigate this risk? Start with pre-flight activity by completing thorough daily inspections and pre-flights. Review maintenance logs for trends and ensure that you complete timely power checks. This is a big one. Power checks are your lifeline and don’t take much time to complete. They enhance your awareness of your engine’s performance and can be useful in a trending capacity to indicate deteriorating power output. Complete FOD checks. Foreign object damage (FOD) can rip open your compressor in a heartbeat – tool control and debris sweeps are crucial to stacking the deck in your favour.

It’s also important, once you are airborne, to ask yourself how high you are flying? It amazes me how often helicopter pilots fly at less than 500 feet above ground when transiting from point A to B.

 Minimize your time in high, out-of-ground-effect hovers – although when engaged in external load operations this is almost impossible to avoid. The height-velocity curve identifies the risks in this flight envelope – just don’t stay exposed longer than necessary.

These are some of the strategies for managing the very real risk of engine failure. Statistically, six of you will experience an engine failure this summer. Fly smart, keep your options open, stay aware of potential emergency landing spots and be safe.


Walter Heneghan is the VP of Safety and Quality at Canadian Helicopters. A passionate advocate for aviation safety and sound risk management, the veteran pilot presents his regular column for Helicopters magazine.


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