How should a pilot respond to a sudden instrument failure or autopilot fault during cruise?

• A. Descend immediately to minimum safe altitude
• B. Power up autopilot to reestablish control
• C. Fly manually if necessary, rely on remaining instruments, maintain situational awareness, and follow published or standard emergency procedures
• D. Turn off all instruments

Answer: (C)

When you lose the ability to rely on instruments or the autopilot, your first duty is to keep the airplane under control and fly safely using whatever instruments are still working. The best approach is to fly manually, use the remaining functioning instruments to maintain attitude and altitude, keep a clear picture of where you are in space (situation awareness), and follow the published or standard emergency procedures to manage and resolve the fault.

Hand-flying and cross-checking with the backup instruments keeps you in command of the aircraft and reduces the risk of a uncontrolled deviation. If the autopilot has failed, disconnect or disengage it and take direct control, then use the standby attitude indicator, altimeter, airspeed indicator, and other available instruments to maintain stable flight while you troubleshoot or divert as needed. Following the standard emergency procedures ensures you address the fault systematically and safely.

Descending immediately to a minimum safe altitude isn’t the automatic reply to an instrument or autopilot fault, and turning the autopilot back on to fix the problem may not succeed and can mask a real fault. Turning off all instruments would leave you with no orientation at all, which is highly unsafe.