Height Velocity Diagram shading area meaning?

Height Velocity Diagram shading area meaning?

• A. The shaded area indicates a safe zone for autorotation
• B. The shaded area indicates maximum endurance speed
• C. The shaded area shows where the engine is protected
• D. The shaded area shows altitude/airspeed combinations with insufficient data to demonstrate safe autorotation

Answer: (A)

The height-velocity diagram shows how altitude above the ground and indicated airspeed interact to affect the ability to autorotate after an engine failure. The shaded region is the safe autorotation envelope: within this area you have enough height and rotor energy (via rotor RPM) to perform a controlled autorotation and reach a safe landing. Being outside this shaded zone means you’re in a combination of height and airspeed that makes a safe autorotation unreliable or impossible. This isn’t about maximum endurance speed, nor about engine protection, and it doesn’t indicate data deficiency—the shading specifically marks where autorotation can be conducted safely.

The height-velocity diagram shows how altitude above the ground and indicated airspeed interact to affect the ability to autorotate after an engine failure. The shaded region is the safe autorotation envelope: within this area you have enough height and rotor energy (via rotor RPM) to perform a controlled autorotation and reach a safe landing. Being outside this shaded zone means you’re in a combination of height and airspeed that makes a safe autorotation unreliable or impossible.

This isn’t about maximum endurance speed, nor about engine protection, and it doesn’t indicate data deficiency—the shading specifically marks where autorotation can be conducted safely.