Contributing Factors In Helicopter Crashes

by James T. Crouse on May 10, 2011

in Helicopter Safety

In February we began a series on the causes of helicopter crashes, so I consider it very timely that Katy Waldman from The Slate Magazine recently contacted me for an article on about the causes of helicopter crashes.

As I discussed with Ms. Waldman, there is no simple answer to why the helicopter accident rate is higher than the commercial fixed-wing accident rate. Helicopters are complex machines with hundreds of moving parts that airplanes don’t have, and they frequently operate in environments that are hazardous. For example, a medical evacuation helicopter rescuing an accident victim at night has likely never been to the location of the victim, will be operating close to the ground and must avoid wires, trees, and even birds, could be presented with a less-than-ideal landing area, and may encounter bad weather—thunderstorms, rain showers, ground fog—en route.

Additionally, there is frequently only one flight crew member on board, depriving the operation of another set of eyes, ears and judgment. Also, many operators do not have adequate flight following and monitoring from their base of operations, which is not conducive to aviation safety. Airliners, in contrast, and followed by that airlines’ base of operations not only in flight, but also while on the ground.

All of these factors contribute to operational errors as being the primary cause of helicopter crashes. Note this is distinct and different from “pilot error,” and involves much more than a pilot simple making a mistake. It is the universe of interrelated facts that come together to cause a regrettable outcome.

Then there are the problems with the equipment itself. Most frequent mechanical cause of helicopter crashes is engine trouble, which can be reduced if the aircraft is equipped with two engines. Also impacting the accident rate are hydraulic system malfunctions or failures, and failures of components—especially rotor system components—by fatigue or overload, or simple undetected wear, and corrosion. Rotor blades can delaminate (split into thin layers), which causes crashes. Finally, electrical problems in today’s highly sophisticated and instrumented helicopters can cause problems with navigation and caution and warning systems.

We will continue our reporting on the International Helicopter Safety Team’s analysis of the causes of helicopter crashes in the upcoming weeks. But we thought this overall view was appropriate now in light of Ms. Waldman’s article.


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