The operator shall not operate a helicopter beyond 10 minutes flying time at normal cruising speed from land when the weather report or forecasts available to the pilot-in-command indicate that-
(a) the water temperature will be less than 10°C during the flight; or
(b) the estimated rescue time exceeds the calculated survival time,
unless each person on board is wearing a survival suit: Provided that this provision shall not apply where an operator received the prior written approval of the Director to operate without such survival suits.