What does "glide ratio" indicate in gliding?

Glide ratio is a key concept in gliding, as it quantifies the efficiency of a glider's performance in the air. Specifically, it indicates the rate of descent compared to the horizontal distance traveled. A glide ratio expresses how far a glider can travel forward horizontally in relation to the altitude it loses during descent. For instance, a glide ratio of 15:1 means that for every 1 unit of altitude lost, the glider can travel 15 units horizontally.

This ratio is crucial for pilots because it helps them understand how far they can glide to a landing zone and assists in optimizing flight paths to maximize distance while managing altitude loss effectively.

Other options address different concepts that do not pertain directly to glide ratio. For example, ascent speed and airspeed relate to climbing and maneuvering capabilities, fuel efficiency is essential in powered flight rather than gliding, and the passenger capacity of the glider deals with load management rather than aerodynamic performance. Hence, the focus on glide ratio as it relates to distance versus altitude is what makes this choice the correct one.