check:
Lose an engine now most will recover and fly away with about 10 ft to spare based on a 100ft helideck
Aren't you supposed to clear all obstacles by 35ft (JAR-OPS 3 and all that)? I imagine the 35ft is there to allow for variations in pilot technique etc eroding the margin. If the margin's only 10ft it's surely not a margin. If you're at 10ft and still not at Vtoss you still only have one option - keep it going down to give you enough speed to climb.
And what about at night?
NS