Technically, the answer is no more than yes. The vanes will only give you a correct direction of wind when in a stationary hover.
If you are moving in any direction you will have a forward component which will alter the direction on ther vanes. So whilst moving in any direction (the faster the worst it will be) then the vanes are a poor indication of wind direction.
However, what they are good at is showing you the RELATIVE air flow for any given direction and speed. (In a hover the relative air flow equals the wind direction - provided the downdraft of the blades does not affect the vanes)
Last edited by bogusheadbox; 02/09/12 06:28 PM.