How is it possible for a subsonic commercial plane to be flying faster than the speed of sound?
Well, it is and it isn’t. It’s fully plausible that the plane in question was traveling at 750 knots, sure, but that’s groundspeed, not airspeed. Velocity over the ground and velocity through the air can be, and usually are, different things. Say a plane is flying in still, windless air at 300 knots. Kick in a 200-knot tailwind, and relative to the ground you’re now at 500 knots. However, the plane’s “true” speed, relative to the air itself, remains where it was at 300. The reverse is true too. Imagine that same plane fighting a 200-knot headwind. Those 300 knots of airspeed equal only a hundred over the surface. Remember that a plane pays no mind to how fast, or in what direction, it moves across the ground. It is the flow of air under and around the wings that keeps the damn thing from dropping out of the sky, and so it cares only how fast it is moving through the air. This is why pilots prefer taking off and landing into the wind, reaping the benefit of free airspeed. If a plane is