Which device is used to measure the passage of time in an aircraft?

The clock is the primary device used to measure the passage of time in an aircraft. In aviation, accurate timekeeping is crucial for various operational reasons, including navigation, fuel management, and coordination with air traffic control.

A clock helps pilots track elapsed time during flight segments, which is essential for maintaining schedules, estimating arrival times, and managing fuel consumption. It can also be used during maneuvers that are time-sensitive, such as holding patterns or timed descents.

In contrast, the magnetic compass, turn-and-slip indicator, and attitude indicator serve different functions. The magnetic compass is used for navigation by indicating the aircraft's heading relative to magnetic north. The turn-and-slip indicator helps pilots understand the rate of turn and coordination of the aircraft during maneuvers, while the attitude indicator displays the aircraft's orientation relative to the horizon, helping pilots maintain controlled flight. While all these instruments are vital for safe operation, none are designed specifically to measure the passage of time as the clock does.