What are standby instruments?

• A. The backup radios.
• B. The auxiliary lighting.
• C. The aircraft's backup instruments that provide essential flight data if primary instruments fail or are unreliable.
• D. The primary attitude indicators.

Answer: (C)

Standby instruments are the aircraft’s backup instruments that provide essential flight data if the primary instruments fail or are unreliable. They’re designed to stay available even when the main systems have issues, often powered by a separate or independent source so a loss of main power or a single system failure doesn’t leave you without basic orientation and flight information. In practice, this set usually includes an attitude indicator for pitch and bank, an altimeter for altitude, and an airspeed indicator, with an additional instrument like a turn/heading indicator to help maintain situational awareness. These tools let you maintain control and continue safe flight while you troubleshoot or switch to alternate procedures. They aren’t radios or lighting, and they aren’t the primary flight instruments; they serve as a reliable fallback when the main instruments are not dependable.