What must be turned off when holding above FL310?

• A. Half bank angle
• B. Autopilot
• C. Flaps
• D. Anti-skid

Answer: (A)

When you’re holding at very high altitude, the air is thin and lift is limited, so altitude becomes highly sensitive to even small changes in bank. To keep the airplane stable in the hold and avoid overshooting or losing altitude, you use a very shallow turn. That means reducing the bank to a much smaller value—roughly half of the usual bank angle. By “turning off half bank angle,” you’re effectively limiting the turn to a shallow bank, which minimizes vertical excursions and helps maintain a steady altitude and spacing in the hold.

Other items don’t address the stability of the hold at high altitude: autopilot operation isn’t the defining change for the hold’s stability, flaps aren’t used in cruise, and anti-skid isn’t relevant to the holding maneuver. The shallow-bank approach directly targets maintaining a clean, smooth hold above FL310.