Wednesday, February 25, 2015

Unknown aircraft performance contributed to float plane accident in Port McNeill, British Columbia: Cessna 185E Skywagon, Air Cab, C-FQGZ

A commercial Air Cab float plane crashed on West Cracroft Island, killing three persons, because a pilot new to the company was unaware of how multiple modifications affected the airplane's performance and handling, the federal transportation safety board has determined.

Pilot Kevin Roger Williams, 42, and two passengers, Norm Slavik, 58, and Frederick Wiley, 40, died after the Cessna C-185E stalled while preparing for landing and crashed onto a small island on Potts Lagoon east of Port McNeill at 11:40 a.m. on Oct. 24, 2013.

In a report released Wednesday, the board said the pilot had accumulated about 3,137 hours total flight time, 1,682 hours of those in seaplane operations.

The pilot had started working for the company 10 days before the accident. The accident occurred on the pilot’s first day of unsupervised flying for Air Cab. The pilot had not flown to the Potts Lagoon area and had not flown the accident aircraft before the day of the accident.

The airplane had received multiple approved modifications over the years, and the pilot would not have known how all these would have changed the performance of the airplane.

"The aircraft’s high bank angle, steep descent, short wreckage trail, and low airspeed were consistent with the occurrence of an accelerated aerodynamic stall at an altitude from which recovery was not possible," the board found.

Because the modifications resulted in performance and handling characteristics unique to the aircraft, the actual stall speed of the aircraft "remained unknown and could only be estimated" and may have compromised the ability of the stall warning system to indicate an impending stall. An advanced stall warning system may have made a difference.

The board concluded that the "installation of multiple modifications without adequate guidance on how to evaluate and document the effects on aircraft handling" may result in pilots losing control due to unknown aircraft performance.

Story and photos: 

RICHMOND, BC, Feb. 25, 2015 /CNW/ - In its report into a 2013 British Columbia (B.C.) float plane accident (A13P0278), the Transportation Safety Board of Canada (TSB) expressed its concern that, if multiple modifications are made without adequate documentation of the effects on aircraft handling, pilots may lose control of the aircraft due to unknown aircraft performance.

"Pilots need accurate information on how an aircraft will fly after modifications have been made to it," said Joseph Hincke, TSB Board Member. "We are concerned that this information is not available consistently and that accidents will continue to occur as a consequence."

On 24 October 2013, a CBE Construction Ltd. (Air Cab) Cessna C-185E float plane left Port McNeill, B.C. water aerodrome with a pilot and 2 passengers on board for a charter flight to West Cracroft Island, B.C. At 1140, while maneuvering for landing on water, the aircraft experienced an accelerated aerodynamic stall while being flown at an altitude from which recovery was not possible before it collided with the terrain on a small island in Potts Lagoon, West Cracroft Island. The aircraft was destroyed and the 3 occupants were fatally injured.

The investigation found that several approved modifications (Supplemental Type Certificates or STCs) had been made to the aircraft that resulted in undocumented performance and handling characteristics and that the pilot's expectation of the aircraft's performance capabilities may not have been accurate. The investigation also identified a risk if multiple modifications are installed without adequate guidance on how to evaluate and document the effects on aircraft handling and performance. Further, there is an increased risk of stall accidents if advanced stall warning systems, such as angle of attack indicators, are not incorporated on aircraft.

Air Cab has begun emphasizing an awareness of aircraft modifications and their effect on aircraft handling during pilot initial and recurrent training. It is also in the process of implementing a G switch on its aircraft tracking system as a back up to the aircraft's electronic locator transmitter, and installing a disconnect G switch on its aircraft batteries to reduce the risk of a post-crash fire, in response to other issues identified during the investigation.

In November of 2014, the TSB announced that it would conduct a Safety Issues Investigation into Canadian air taxi operations to understand the risks that persist in this important sector of the aviation industry. The study will engage industry, the regulator and other stakeholders to gain a full understanding of the issues affecting air taxi operations. The Board may make recommendations to address any identified systemic deficiencies.

The TSB is an independent agency that investigates marine, pipeline, railway and aviation transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.

SOURCE Transportation Safety Board of Canada

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