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.

Commercial planes in 2026 typically cruise at 30,000 to 40,000 feet for two primary reasons: fuel efficiency and weather avoidance. At higher altitudes, the air is "thinner" (less dense), which creates less aerodynamic drag on the aircraft. This allows the plane to fly faster while burning significantly less fuel, which is the single biggest cost for airlines. Furthermore, the jet engines themselves operate more efficiently in the cold, thin air of the upper troposphere. Secondly, most "weather"—including thunderstorms, heavy rain, and the thickest clouds—occurs in the lower atmosphere. By flying high, planes can cruise above the storm systems, leading to a much smoother and safer ride for passengers. Flying at this height also provides a "safety buffer"; if an engine fails, the pilot has more time and distance to glide the aircraft toward a suitable emergency landing site.