What does the vertical speed indicator show when climbing?

The vertical speed indicator (VSI) is an essential instrument in an aircraft's cockpit, designed to display the rate of ascent or descent relative to the ground. When a plane is climbing, the VSI registers positive values, which indicate an upward trend in altitude.

This information is crucial for pilots as it enables them to monitor their ascent rate effectively. The measurement is typically expressed in feet per minute or meters per second, and a reading of positive values demonstrates that the aircraft is gaining altitude. For instance, if the VSI indicates a rate of climb of 500 feet per minute, it means the aircraft is ascending steadily.

Understanding the VSI's function is vital for a pilot's situational awareness and flight management. In contrast, negative values would arise during descent, while zero values indicate level flight. Erratic readings could suggest mechanical issues or rapid changes in flight attitude, which typically do not occur in steady climbs. Therefore, the vertical speed indicator accurately reflects positive values during climbing, making this the correct answer.