Why Does a Flight's ETA Change?

A flight’s ETA changes because it is a prediction that is recalculated as conditions change. Wind, air traffic, routing and weather can each add or remove minutes.

What affects ETA

• Wind. A stronger tailwind than forecast means an earlier arrival; a headwind a later one.
• Routing. Air traffic control may clear a more direct route, or send the aircraft on a longer path to keep separation.
• Speed changes. Controllers can ask aircraft to slow down or speed up to sequence arrivals.
• Holding and vectoring. Busy airports can make aircraft hold or fly extra legs. See holding pattern.
• Weather. Thunderstorms and fog can force detours, diversions or runway changes.
• Runway and gate availability. An aircraft can land and then wait for a free gate.

Two kinds of ETA

Airlines produce an official ETA using flight plans and operations data. A tracker without airline data can only compute a rough time from distance and speed. On this site, the “estimated time to airport” on airport boards is distance divided by ground speed and is only a guide.

What to expect

Changes of 5 to 15 minutes close to landing are common. Do not rely on an ETA more than an hour ahead to the minute.

Tip

For airport pickups, wait for “landed” and allow time for formalities; see landed vs arrived. Also read scheduled vs estimated vs actual time.

General information only, not legal or safety advice. Details change; check with your airline and the relevant authority. See our editorial policy.