A typical commercial jet, like a Boeing 737 or an Airbus A320, cruises at about 550 to 600 miles per hour (885 to 965 kilometers per hour). That’s roughly Mach 0.85, which is 85% of the speed of sound. For perspective, that’s almost as fast as a .22 caliber bullet leaves the gun—though hopefully your plane is not shooting anything.
But here’s the kicker: that speed is relative to the air around it, not the ground. Thanks to jet streams, a plane can fly at 600 mph through the air but zip over the ground at 800 mph with a tailwind. Conversely, headwinds can make you feel like you’re stuck in a cosmic traffic jam, crawling along at 400 mph. That’s why your flight home from LA to New York is an hour shorter than the reverse trip—physics is a fickle mistress.
