For many operators the HV envelope is of significant importance when operating Public Transport / Commercial Air Transport Flights.
ICAO Annex 6 Part III, Chapter 3, Para 3.1.2 requires that “Performance Class 3 helicopters shall only be operated…over such routes…that permit a safe force landing to be executed in the event of an engine failure.” This of course includes the arrival and departure phase where the HV envelope becomes critical. How often do you see a Bell 206 or AS 350 punch straight up through the HV envelope when taking off? I would suggest frequently!
It is important, in order to comply with this requirement, to avoid the HV envelope and ensure that the terrain surface is appropriate to a forced landing at all times (as addressed by Shawn Coyle in an earlier post).
Thankfully this is not a requirement for aerial work, where ICAO Annex 6 does not apply. However for some operators it becomes an issue for aerial photography and filming flights which are now being classified as Public Transport / Commercial Air Transport flights by many regulatory authorities. Operating at low speed and at low altitudes on aerial photography and filming flights is frequently “challenging”.