Treg,
UK CAP 437 (Used a a standard document for helideck inspections in virtually all non FAA locations worldwide) refers to Air Turbulence in three places.
- Once with reference to operations to merchant vessels fitted with non standard landing areas.
- Once with reference to poop deck operations to vessels.
- Once in the suggested check list to be used during any deck inspection.
Bottom line is that it is up to a qualified deck inspector (usually HCA trained) of the helicopter operator (or HCA inspector in the UK or overseas if they are so contracted) to identify areas of possible turbulence for specific relative wind conditions for a helideck on any structure.
The findings will then be included in the helideck clearance report often included in the Operations Manual Part C (for JAR compliant ops)
For fixed structures, the "turbulent sectors" will often have a maximum wind speed and direction for unrestricted/restricted or NO Operations.
Much more to this than originally meets the eye.
Cheers
Trog