How to Read Altitude, Speed and Vertical Rate
On a flight tracker, altitude shows how high the aircraft is, speed shows how fast it moves over the ground, and vertical rate shows whether it is climbing or descending. Together they show the phase of flight.
Altitude
Altitude is shown in feet (and sometimes metres). Airliners cruise between about 31,000 and 41,000 feet. Below about 10,000 feet an aircraft is usually taking off or approaching an airport. A value of 0 or “on ground” means the aircraft is on the surface. See flight level and cruise altitude.
Speed
Speed is shown in knots (nautical miles per hour) or km/h. It is normally ground speed, so wind affects it. A typical airliner cruises at 430 to 520 knots (800 to 960 km/h) ground speed. Near landing the speed falls to about 130 to 160 knots.
Vertical rate
Vertical rate is in feet per minute (ft/min). Positive means climbing; negative means descending. A typical climb is 1,500 to 3,000 ft/min; a typical descent about 1,500 to 2,500 ft/min; 0 means level flight.
Reading the phase of flight
- Low altitude, high positive vertical rate: climbing after takeoff.
- High altitude, near-zero vertical rate: cruising.
- Decreasing altitude, negative vertical rate: descending towards landing.
- Low altitude, low speed near an airport: approaching or taxiing.
Accuracy
Altitude is usually from the pressure altimeter and can differ from height above the ground. See how accurate is flight tracking.
General information only, not legal or safety advice. Details change; check with your airline and the relevant authority. See our editorial policy.