Thanks Mike, and would you know the sort of heights and speeds used? And whether the helps hover much while surveying?
We used to do ours fortnightly on an exemption to 200ft and at a notional 80Kts. Hover is of no particular use - you can orbit if needed for a closer look. Landing out was only ever in extreme cases (A Hymac actually found digging on the easement for instance) In reality of course it was flown as fast as you could go.