What instrument indicates the actual horizontal speed of the helicopter as a backup to the primary flight display?

• A. Ground Speed Indicator
• B. Rate of Climb Indicator
• C. Airspeed Indicator
• D. Vertical Speed Indicator

Answer: (C)

The instrument that indicates the actual horizontal speed of the helicopter as a backup to the primary flight display is the airspeed indicator. This instrument provides the pilot with important information about the helicopter's speed relative to the air around it, which is crucial for maintaining effective control and performance during flight.

Understanding airspeed is vital for ensuring safe operation, particularly during takeoff, landing, and maneuvering. The airspeed indicator measures dynamic pressure to determine how fast the helicopter is moving through the air; this is essential for assessing performance and making adjustments as necessary.

While the ground speed indicator provides information on how fast the helicopter is moving over the ground, it does not serve as a direct measure of flight performance like the airspeed indicator does. The rate of climb indicator and vertical speed indicator are concerned with the vertical movement of the helicopter, measuring rate of ascent or descent, rather than horizontal speed. Therefore, the airspeed indicator is the most relevant for indicating actual horizontal speed as a crucial backup instrument.