At which point in steady flight does an airplane achieve its maximum glide range?

An airplane achieves its maximum glide range at the airspeed for maximum lift-to-drag ratio. This point is crucial because the lift-to-drag ratio (L/D) significantly influences an aircraft's ability to glide further without power.

When an airplane is flying at this optimal speed, its lift is maximized relative to the drag. This means that for every unit of altitude lost, the aircraft travels the greatest horizontal distance possible. In simpler terms, maintaining this speed allows the aircraft to cover the maximum distance before reaching the ground after losing power.

In contrast, the options related to maximum endurance speed, stall speed, or cruising speed do not optimize the lift-to-drag relationship in the same way. Maximum endurance speed focuses on remaining airborne for the longest time rather than maximizing distance, stall speed significantly increases drag and reduces lift, and cruising speed may not necessarily be at the ideal L/D ratio compared to the optimal glide speed. Thus, maximizing lift-to-drag ratio is the key factor in achieving the best glide performance.