What characteristic of the Turn Coordinator helps maintain straight flight?

The Turn Coordinator is a vital instrument in an aircraft, primarily used to aid in maintaining coordinated flight during turns. When flying straight and level, the Turn Coordinator typically shows a ‘zero’ indication, which reflects no bank angle. As the pilot begins a turn, the Turn Coordinator displays the bank angle, allowing the pilot to monitor and adjust the aircraft's attitude effectively.

Maintaining the correct bank angle is crucial for coordinated turns, which helps prevent uncoordinated flight conditions such as skidding or slipping. An appropriate bank angle ensures that the horizontal component of lift is aligned with the turn, leading to smoother and more controlled maneuvers. Therefore, the Turn Coordinator's ability to indicate the degree of bank during turns is essential for maintaining straight flight, particularly when transitioning from straight and level to a turn.

The other options do not relate directly to the function of maintaining straight flight. Altitude measurement is typically provided by the altimeter, engine performance tracking involves various engine instruments, and weather alerts are managed by different systems or devices altogether. Thus, the Turn Coordinator's primary role in indicating the bank angle directly supports the pilot in maintaining not just a straight flight but also in executing smooth turns.