Speed and altitude: record ground speeds and unusual heights

Ground speed is how fast an aircraft moves over the ground, so a strong tailwind can push an airliner well past its usual speed without the aircraft flying any faster through the air. In winter the jet stream can add well over 100 knots. Altitude has its own catch: aircraft report pressure altitude from their instruments and often a geometric altitude from satellite positioning, and the two can differ by hundreds of feet.

The site keeps the fastest sustained ground speed for each aircraft type this season, using only reports the aircraft broadcast itself for at least a minute, and writes a story when a new one is set. A record counts once at least 20 aircraft of the type have been recorded this season, and never above 900 knots or the type's listed limit. Some aircraft also report their true airspeed; when the ground speed runs 100 to 300 knots higher, the difference is the wind's push along the track. A speed or altitude far beyond what a type can fly goes to the ADS-B glitches topic instead, because it points to a bad reading or a wrong type in the database.

A record here covers these records only, for one season. Most reports carry no airspeed, so the wind's share of a fast ground speed is usually unknown, and where an aircraft does report its true airspeed the difference gives a speed along the track without the wind's direction. An unusual altitude is compared with a type's limits only when the story states that comparison. The field guide explains ground speed and the two kinds of altitude in more detail.