Offshore oil companies are grounding helicopter flights over rough seas off Newfoundland as recommended by the Transportation Safety Board.

Paul Barnes of the Canadian Association of Petroleum Producers says Cougar flights will be grounded when sea states are higher than six metres.

Three choppers in the Newfoundland fleet have flotation equipment designed for six-metre waves, but Barnes says they've flown over rougher seas.

The change will affect Cougar helicopter service to the offshore but Barnes says safety must come first.

The Transportation Safety Board reported on a Cougar helicopter crash almost two years ago that killed 17 people.