Subsonic speed refers to any speed that is less than the speed of sound in a given medium, typically air. In standard conditions at sea level, this speed is approximately 343 meters per second (1,125 feet per second). Aircraft flying at subsonic speeds are often more fuel-efficient and quieter than those flying at supersonic speeds. Most commercial airplanes, such as the Boeing 737 and Airbus A320, operate at subsonic speeds during flight. This allows them to transport passengers and cargo safely while minimizing noise pollution and fuel consumption. Subsonic speeds are crucial for everyday air travel and are essential for maintaining air traffic safety.