Height Velocity Diagram

The height/velocity diagram is a graph of the safe/unsafe flight profiles relevant to a specific helicopter.  As operation outside the safe area of the chart can be fatal in the event of a power failure, it is sometimes referred to as the dead man’s curve by helicopter pilots. By carefully studying the height/velocity diagram, a pilot is able to avoid the combinations of altitude and airspeed that may not allow sufficient time or altitude to enter a stabilized autorotative descent.

 

The height-velocity diagram can be found in the Pilot’s Operating Handbook.

The diagram shown here is for a Robinson R44 helicopter, but they’re all very similar. The idea is to stay out of the shaded area. Generally speaking, you want either altitude or airspeed — or (preferably) both. Hovering in the 10-400 foot range puts you inside the “deadman’s curve.”

The height velocity diagram also clearly shows the recommended take-off profile.