A more ominous epithet for the HV diagram — but one commonly used in the field — is “dead man’s curve.”A twin-engine Airbus H145, operated by Heli Austria, perform hoisting operations in the Alps. This need for height and/or speed gives rise to a shaded “avoid” area in the HV diagram. The HV diagram appears in almost every helicopter flight manual (the Sea King is an exception). The analytical model is validated by flight tests that cover engine failure, “lever delay” tests, and engine-off landings (EOL). Lloyd Horgan PhotoOn light singles, expect to find no more than a single HV diagram in the RFM, since no “fly away” is possible.