During IFR flight, which instrument provides magnetic direction when the heading indicator is unreliable?

• A. Turn coordinator.
• B. Altimeter.
• C. VSI.
• D. Magnetic compass.

Answer: (D)

Magnetic direction is provided by the magnetic compass. It’s a separate, non-gyro instrument that directly shows heading relative to magnetic north, so it remains usable even when the heading indicator (the gyro-based directional instrument) is unreliable. The compass is powered mechanically or magnetically and gives you a basic sense of heading, which you can cross-check with other navigation sources. It does have known limitations—such as lag in response to turns and acceleration errors—but it’s still the instrument that provides magnetic heading when the heading indicator isn’t trustworthy. The other instruments listed don’t give magnetic direction: the turn coordinator shows turn rate, the altimeter shows altitude, and the VSI shows vertical speed.