Unexplained altitude drop forces offshore helicopter to return to airport

An offshore helicopter flying from Halifax airport to ExxonMobil’s Thebaud platform offshore Nova Scotia has experienced an unexplained drop in altitude, forcing the pilots to return to the airport, according to Canada-Nova Scotia Offshore Petroleum Board (CNSOPB).

Thebaud platform; Source: CNSOPB

CNSOPB, a government regulator in charge of petroleum activities in the Nova Scotia Offshore Area, informed on Thursday that ExxonMobil had reported a helicopter occurrence with respect to a flight that was en route with two pilots and 11 passengers to the Thebaud platform.

According to the regulator’s incident bulletin, on July 24, 2019, a Sikorsky S-92 helicopter operated by Canadian Helicopters Offshore (CHO) experienced an unexplained drop in altitude as it approached the Thebaud platform. Once serviceability was confirmed, the helicopter pilots made the decision to return to the heliport at the Halifax International Airport with its passengers, the regulator said.

There were no injuries reported associated with this incident, which has been reported by CHO to Transport Canada Civil Aviation (TCCA) and the Transportation Safety Board (TSB).

This incident remains under investigation by ExxonMobil and CHO, and is being monitored by the CNSOPB. CHO has suspended passenger flights to offshore platforms until the cause of the incident is understood and any corrective actions that are required have been implemented.

The Thebaud platform is part of ExxonMobil-operated Sable project, which is made up of seven offshore platforms in five different fields with 21 wells, and 340 kilometers of subsea pipeline. The fields are Thebaud, North Triumph, Venture, Alma, and South Venture.

The development is spread over 200 square kilometers near Sable Island in the North Atlantic Ocean. The seven platforms are located in shallow water with depths between 22 and 76 meters.

Interfield pipelines connect satellite fields to the central Thebaud complex, which is made up of a processing facility and accommodations unit, a wellhead platform and a compression deck.


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