In a conventional flight instrument system, the autopilot altitude hold information is provided by which device?

• A. Autopilot aneroid
• B. Flight data recorder
• C. Horizontal situation indicator
• D. Cabin pressure controller

Answer: (A)

Altitude hold relies on a pressure-based signal created specifically for the autopilot by the autopilot’s own sensing element—the autopilot aneroid. This device converts static pressure into a signal the autopilot can use to control pitch and maintain the selected altitude. It’s tied into the aircraft’s pitot-static system but is dedicated to steering the autopilot, giving it accurate altitude information to hold steady.

The other options don’t provide altitude data to the autopilot: a flight data recorder logs flight parameters after the flight, a horizontal situation indicator shows heading/navigation information, and a cabin pressure controller manages cabin pressurization, not autopilot altitude control.