The Airworthiness Investigative Authority for the Canadian Armed Forces has concluded its flight safety investigation into the accident that occurred on April 29, 2020 in the Ionian Sea involving a CH-148 Cyclone helicopter that claimed the lives of six Canadian Armed Forces members. The helicopter, known by its call-sign Stalker 22, was operating from Her Majesty's Canadian Ship Fredericton as part of Standing NATO Maritime Group 2 under Operation REASSURANCE.
Lost in the accident were Master Corporal Matthew Cousins, Sub-Lieutenant Abbigail Cowbrough, Captain Kevin Hagen, Captain Brenden MacDonald, Captain Maxime Miron-Morin, and Sub-Lieutenant Matthew Pyke.
The complete findings of the investigation and recommendations are released today and detailed in the CH148822 Flight Safety Investigation Report.
The investigation concluded that during a complex turning manoeuver at low altitude, when the helicopter was returning to the ship, the aircraft did not respond as the crew would have expected due to a Command Model Attitude Bias Phenomenon. This phenomenon develops under a very specific and narrow set of circumstances where manual inputs to the primarily flight controls override the aircraft's automation system, referred to as the Flight Director, while it is engaged and set to fly at a fixed airspeed or pitch attitude. The bias that developed in this instance resulted in insufficient aft cyclic controller authority, resulting in a high-energy descent and impact with the water.
A series of other causal factors were highlighted in the report, to include:
- Control inputs when flying with the Flight Director engaged were not verbalized in the cockpit,
- Flying publications contained information that may have been confusing or misleading,
- The Statement of Operating Intent for the CH-148 did not specify the operational requirement to fly the manoeuver involved in the accident,
- Standard operating procedures for this manoeuver were undocumented,
- It was common practice to manually override primary flight controls while the Flight Director was engaged, and
- The mode annunciation may not have sufficiently drawn the pilot's attention to the fact the Flight Director was engaged during the manoeuver.
Recommendations include the need to modify software in the electronic flight control laws to enhance flight mode annunciation and awareness to the crew, amend CH-148 publications regarding automation strategies, and establish a working group to review the Maritime Helicopter Project Statement of Operating Intent. This review will determine the CH-148 operational requirements to fly complex turning manoeuvers, including the one that led to this accident.
