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 jets fly at approximately 35,000 to 38,000 feet primarily for fuel efficiency and weather avoidance. At this altitude, the air is significantly "thinner," which reduces aerodynamic drag on the aircraft. This allows the plane to travel faster while burning less fuel, making it the highest-value altitude for long-haul "cruise" segments. Furthermore, 35,000 feet is generally above the Troposphere, where most of the world's "bad weather" (storms and turbulence) occurs. By flying in the lower Stratosphere, jets enjoy a much smoother ride and avoid the high-stress structural loads caused by convective weather. There is also a "jet engine" benefit: turbofan engines operate most efficiently in the cold, thin air of the upper atmosphere. A high-value technical detail is the "Coffin Corner"—if a jet flies too high, the thin air can cause an aerodynamic stall, so 35,000–41,000 feet is the "Sweet Spot" where speed, safety, and fuel savings are perfectly balanced for modern 2026 aviation.