Sikorsky S-92A Near-Loss of Altitude During Offshore Departure

Casualties unknown • St. John's, Newfoundland and Labrador, 200 nm E, CA

A Cougar Helicopters S-92A experienced a dangerous nose-high descent and nearly struck the ocean surface during a departure from a production vessel in Newfoundland and Labrador.

What happened

On 23 July 2011, a Sikorsky S-92A helicopter, registration C-GQCH, was departing the Sea Rose floating production, storage, and offloading vessel in Newfoundland and Labrador. The aircraft, operated by Cougar Helicopters, was carrying two crew members and five passengers. During the departure, the captain applied a rapid aft cyclic input, which caused the aircraft to enter a decelerating, nose-high pitch attitude.

As the pilot engaged the go-around mode of the automatic flight control system, the aircraft's airspeed dropped significantly. The helicopter entered an unusual attitude with a 23° nose-up pitch, leading to a rapid descent through a thick cloud layer. The aircraft's descent rate peaked at 1880 feet per minute, bringing the helicopter within only 38 feet of the water's surface. The crew eventually arrested the descent with an aggressive application of collective, which caused the transmission torque limits to be exceeded. There were no injuries and no damage to the aircraft.

The investigation

The TSB examined the flight dynamics, the performance of the automatic flight control system, and the crew's response to the emergency. The investigation looked into the functionality of the S-92A's enhanced ground proximity warning system (EGPWS) and the limitations of the go-around (GA) mode. Investigators also reviewed the operator's standard operating procedures (SOPs), crew training, and the effectiveness of crew resource management (CRM) during the incident.

Findings

The primary cause of the incident was the captain's large, rapid aft cyclic input just before engaging the go-around mode, which induced a nose-high, decelerating pitch.
The S-92A's go-around mode has reduced control authority, which hindered the aircraft's ability to recover from the established unusual attitude.
The captain experienced a period of subtle incapacitation, possibly due to spatial disorientation, failing to promptly lower the nose and apply collective.
The first officer did not take control of the aircraft despite the company's "two-challenge rule," likely due to a lack of confidence in his manual flying skills during instrument conditions.
The EGPWS provided no warning of the descent at airspeeds below 40 knots while the landing gear was in the up position.
The aircraft's Rotorcraft Flight Manual (RFM) contained misleading guidance regarding the use of the GA mode for recovering from unusual attitudes.

Probable cause

The incident was caused by an improper manual flight input that induced a nose-high attitude, compounded by the limitations of the aircraft's automation and the crew's failure to execute manual recovery procedures.

Frequently asked questions

What happened in the 2011-07-23 Sikorsky S-92A (Helicopter), C-GQCH accident near St. John's, Newfoundland and Labrador, 200 nm E, CA?

A Cougar Helicopters S-92A experienced a dangerous nose-high descent and nearly struck the ocean surface during a departure from a production vessel in Newfoundland and Labrador.

What aircraft was involved and where did it happen?

The accident on 2011-07-23 involved a Sikorsky S-92A (Helicopter), C-GQCH, operated by Cougar Helicopters Inc., at St. John's, Newfoundland and Labrador, 200 nm E, CA.

What was the probable cause of the accident?