Your pilot announces you’re cruising at 530 miles per hour. Meanwhile, the GPS on your phone shows 580. Which one’s right? Both are, technically. Welcome to the confusing world of aviation speed measurement.
Why There Are Multiple “Speeds”
Aviation uses several different speed measurements because each serves a specific purpose:
Indicated airspeed (IAS) is what the cockpit instruments show. It comes from comparing the pressure of air ramming into the front of the aircraft (through a pitot tube) against the static air pressure. This number matters for aerodynamics – stall speeds, flap operating limits, and structural limits are all specified in IAS.
True airspeed (TAS) is how fast you’re actually moving through the air mass. At altitude, where air is thinner, your IAS underestimates your actual speed. A 737 showing 280 knots on the airspeed indicator at 35,000 feet is actually moving through the air at around 450 knots true.
Ground speed is how fast you’re moving relative to the ground below – what your phone’s GPS displays. Add a 100-knot tailwind to that 450-knot true airspeed and you’re covering ground at 550 knots. Turn around and fly into that same wind, and you’re down to 350 knots over the ground despite the same engine thrust.
Typical Speeds by Aircraft Type
Numbers that actually mean something to passengers:
Regional jets (CRJ, Embraer) cruise around 450-500 mph ground speed. These smaller jets fly slightly lower and slower than mainline aircraft.
Narrowbody jets (737, A320) typically cruise at 470-530 mph. The specific speed varies with wind, weight, and how much the airline wants to save on fuel versus getting somewhere on time.
Widebody jets (777, A350) cruise at similar speeds, sometimes slightly faster. The 787 tends to run a bit quicker than its competitors.
Private jets vary enormously. A Cessna Citation might cruise at 400 mph. A Gulfstream G650 pushes 600 mph – faster than most commercial flights.
Why Not Fly Faster?
Physics fights you. Air resistance increases with the square of velocity – double your speed and you quadruple the drag. That means quadrupling fuel consumption to go twice as fast. Airlines found the sweet spot decades ago: somewhere around Mach 0.78-0.85 (78-85% of the speed of sound).
Approaching Mach 1 creates shockwaves that dramatically increase drag. The Concorde solved this by pushing through to Mach 2.04, where the efficiency curve becomes manageable again. But its fuel burn was astronomical – it consumed roughly four times more fuel per passenger-mile than a modern subsonic jet.
Getting Faster (Maybe)
Several companies are working on new supersonic business jets. Boom Supersonic’s Overture promises Mach 1.7 with better economics than the Concorde. Whether that works economically remains to be seen.
For most passengers, the honest answer is: speeds aren’t going up anytime soon. A 787 today cruises at roughly the same speed as a 707 did in 1958. The improvements have come in fuel efficiency, comfort, and range – not velocity.
That 530 mph announcement from your pilot? It’s going to stay roughly there for the foreseeable future.
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Pilots Handbook of Aeronautical Knowledge – $25.42
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