A17O0264 (Tweed) Opening remarks
Kathy Fox, TSB Chair
Ewan Tasker, Manager, Air Investigations Ontario Region
Richmond Hill, ON, Ontario
31 January 2019
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On December 14, 2017, an Airbus Astar helicopter owned by Hydro One Networks collided with terrain while transporting power line technicians near Tweed, Ontario. The pilot and all three passengers were fatally injured. Within one week of the accident, the Transportation Safety Board of Canada revealed that one bag that was inadequately secured blew off from an external platform, struck the tail rotor in flight, and rendered the aircraft uncontrollable.
Today, the TSB is releasing its full investigation report. We are also issuing a recommendation: that Transport Canada remove any ambiguity associated with the definition of “safety belt” in the Canadian Aviation Regulations. This measure would ensure that both the shoulder harness AND lap straps are used in conjunction, increasing the odds that passengers survive a crash.
I'll talk more about that recommendation in a few minutes, but first I'll turn things over to Ewan Tasker. He is going to walk you through exactly what we learned, explaining how and why events unfolded that morning.
At 11:44 on the morning of the occurrence, the pilot picked up three power line technicians at the base of a tower to transport them to a nearby staging area for lunch. A large pulley and two large tool bags were secured to an external platform, called an Air Stair, that extends out of the right side of the fuselage. A canvas supply bag was also being carried on the Air Stair; however, it's exact location is uncertain.
Just a few minutes after takeoff, the pilot started the descent to land. The helicopter was 230 feet above ground when the canvas bag blew off the Air Stair and, along with the attached carabiner, struck and severely damaged the tail rotor. This caused intense vibration and imbalance.
Moments later, the tail rotor and the vertical fin detached from the tail boom. No longer controllable, and still 75 feet above ground, the helicopter began to spin. The three passengers subsequently became separated from the aircraft. The helicopter and pilot then crashed into a wooded area 400 feet northwest of the intended landing site. There were no survivors.
The TSB's investigation on this occurrence was detailed and comprehensive. Although we knew “what happened” early on, finding out “why it happened” took much longer. For instance, why was the bag not secured to the Air Stair? And why were the passengers not wearing safety belts?
With respect to the bag, we found it had become common practice for workers to attach tool bags and other small loads to the Air Stair for travel to and from work sites. In fact, there was no formal guidance prohibiting the carrying of small external loads during transit flights.
With respect to the safety belts, the helicopter's rear seats were equipped with 4-point detachable safety belts, each consisting of a lap strap and an automatic locking shoulder harness. We found that two of the three passenger lap straps were unfastened. Furthermore, all three shoulder harnesses were taped up and were not regularly being used. Additional analysis uncovered a more widespread issue: the perception that wearing the shoulder harness is somehow optional as long as the lap strap is used. This perception is not accurate. The intent of the regulations is that aircraft crew and passengers must wear the lap strap and the shoulder harness, whenever it is available.
That's where today's recommendation comes in, and so I'll hand things back to Chair Kathy Fox, who will talk about what needs to be done to make these kinds of flights safer in the future.
Soon after this accident, the TSB issued an Aviation Safety Advisory letter containing two safety messages: first, external cargo must be adequately secured at all times to prevent it from shifting or departing the helicopter during flight; and second, passengers who do not wear safety belts risk serious injury or death in the event of an accident. However, during the course of this investigation, it became apparent that further safety action was required.
The Canadian Aviation Regulations define a safety belt as “a personal restraint system consisting of either a lap strap or a lap strap combined with a shoulder harness.” Because of the word either, it is unclear if both must be worn. Pilots and passengers may therefore interpret this regulation to mean that use of the lap strap alone is sufficient, as was the case in this operation. We want that uncertainty removed.
While the use of both the shoulder harness and the lap strap may not have prevented the fatalities in this particular case, the proper use of safety belts is known to significantly reduce the chance of serious injury or death in the event of any survivable accident.
That's why today we are recommending that the Department of Transport remove any ambiguity associated with the definition of safety belt in the Canadian Aviation Regulations. Until then, we encourage industry and passengers to be proactive. Buckle up. It can save lives.