The maximum speeds of high-technology operational aircraft are seen to increase steadily from about 125 miles per hour in 1920 to nearly 450 miles per hour in the World War II years. The highest maximum speed shown is for the P-51D aircraft, which had a speed of 437 miles per hour at 25 000 feet.

Aircraft speeds in World War II saw a massive technological leap, starting with biplanes and ending with the birth of the jet age. At the start of the war in 1939, most front-line fighters like the early Spitfire or Messerschmitt Bf 109 had top speeds around 330–350 mph. By the middle of the war, advanced piston-engine fighters like the P-51D Mustang reached speeds of approximately 440 mph. The absolute fastest aircraft to see combat were the early jets and rocket planes. The German Messerschmitt Me 262, the first operational jet fighter, could reach roughly 540 mph, making it nearly 100 mph faster than its Allied propeller-driven rivals. Even more extreme was the rocket-powered Messerschmitt Me 163 Komet, which could briefly hit speeds over 600 mph during its climb. In steep dives, some propeller planes reportedly approached the "sound barrier" (approx. 760 mph), though they often suffered structural failure or loss of control due to compressibility before actually reaching it.