Why Is Flight Tracking Data Delayed?

Flight tracking data is delayed because it passes through several steps before it reaches your screen, and each step adds time. The delay is usually a few seconds to a few minutes.

The delay chain

• The aircraft broadcasts once or twice a second, so a position is already up to a second old when sent.
• The receiver decodes the signal and sends it over the internet.
• The network gathers data from many receivers and updates its records.
• The website fetches the data, often caching it to avoid overloading the source.
• Your browser refreshes at intervals.

Free data and caching

Free data sources limit how often they can be queried. A site serving many visitors therefore fetches data on a schedule and shares one copy among visitors. That is how this site works; the age of the data is shown under each map and table.

Smooth movement is not new data

Between updates, many maps move aircraft smoothly using their speed and heading. That makes the map feel live but is an estimate.

Some delays are deliberate

Some services delay data by minutes for aircraft involved in sensitive operations, and some commercial services delay free users’ data.

What it means for you

For tracking a flight to pick someone up, a delay of a minute does not matter. For anything safety-related, trackers are not suitable; air traffic control and airlines use their own systems. 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.