Archive note: This page was published in March 2019 after reports of unusually high aircraft groundspeeds. The original airline, aircraft, record, percentage, and city-pair timing statements were not supported by durable primary sources and have been removed.
A strong tailwind can increase groundspeed, while a strong headwind can reduce it. Groundspeed is the aircraft's movement relative to the ground; it is not the same as airspeed, and a high reported groundspeed does not mean the aircraft exceeded its certified airspeed limit.
Jet-stream position and strength change with atmospheric conditions. A historical observation cannot be reused as a flight-time estimate for another date or route. Estimated block time must account for the actual route, forecast winds, aircraft, air traffic, airports, and operating plan, and it remains subject to change.
