Wake Turbulence Separation and helicopters
Sorry for intruding onto an ATC forum but I have a question regarding the application of wake turbulence separation between FW and RW.
The reasons for separating FW from FW are obvious since a few knots of differential airflow between one wing and another due to turbulence can be very dangerous leading to stall and loss of control.
On a helicopter, large differences of airspeed exist between one side of the rotor disc and the other all the time, with the rare exception of a still air hover in flat calm conditions, and that difference can be very large, even in the hover on a windy day.
The differences in airflow don't lead to stall or loss of control in a helicopter - even something as light as an R 22 can operate in gusty, bumpy conditions and winds varying far more than in the wake of a 747.
So my question is - why apply the same separation criteria, whether it be distance based or time based, between a FW and a RW?
A second question is, what alleviations are allowed to disregard wake turbulence separation when wind conditions - ie strong crosswind away from other traffic - mean the wake cannot possibly persist and be affecting other traffic?