The biggest reason for flying at higher altitudes lies in fuel efficiency. The thin air creates less drag on the aircraft, which means the plane can use less fuel in order to maintain speed. Less wind resistance, more power, less effort, so to speak.

Even on short flights of 45 to 60 minutes, planes aim for higher altitudes (typically 20,000 to 30,000 feet) primarily for fuel efficiency and speed. The air is much thinner at higher altitudes, which reduces aerodynamic drag, allowing the aircraft to travel faster while burning significantly less fuel. Additionally, flying high moves the aircraft above the "weather"—the turbulent air, clouds, and storms found in the lower troposphere—resulting in a much smoother ride for passengers. While it takes extra energy to climb to these heights, the "cruise" phase is so much more efficient that it almost always offsets the cost of the ascent. However, on extremely short "puddle jumper" routes (under 30 minutes), the plane may never reach a high cruising altitude because the time spent descending would begin almost immediately after the climb, making the maneuver mathematically inefficient. In 2026, flight management systems optimize this "Top of Climb" point to ensure that even short hops capture as much of the thin-air efficiency as possible before beginning the approach to the destination.