"North South" and "Check",
both of you have your wires well crossed. A clearance of obstacles by minimum 35 feet, is a requirement of full blown performance models such as BCAR Group A or CAT A where the helicopter is required (in the event of OEI - an engine failure) to either continue the take-off or land safely, clearing where necessary all obstacles by the prescribed 35 feet.
It is simply not possible to provide an unequivocal performance solution in the offshore environment. This is because of obstacles, turbulence and the inability of the crew to adequatley plan approach paths into predictive wind flow patterns.
To get around this thorny issue the regulators have long since accepted that under certain conditions the loss of an engine could result in a catastrophic crash. Horrific right!! well it would be if that was the end of the story.
To mitigate this risk the regulators require that the engines are maintained to a certain standard, trend checked and subject to a reliability program and monitored in flight with a full HUMS system. These requirements carried out to reduce in so far as possible, the chance of the engine failing.
Also the flight crew are trained and checked in their flying profiles and procedures to minimise the risks of deck edge impact in the event of OEI. Hence the funny vertical climb followed by swift rotation to clear the deck edge.
There are measures afoot to try and increase the performance criteria for offshore helicopters but so far non has come close to being workable.
I, like all my collegues have come to accept this risk much as we do the chances of the tail rotor failing, which under almost all conditions would result in catastrophy during the early phase of flight.
I think until someone comes up with a better design than Igor Sikorsky's basic original we must live with what we have and continue to improve the monitoring and reliability systems that we have to nail down those pesky in service failures before they actually happen.
The system does seem to work very well.
As for the S76 take-off above...he is either showboating or is not at the prescribed AEO HOGE mass. I have no idea where in the world he is so maybe he is not required (like we are under JAR) to operate to this mass.
Taking off downwind when heavy in the offshore environment is just plain stupid......but we have all done it when the wind appears really slack apart from the residual 5 knots that developed up the arse whilst we were refuelling....right!!!
DB