How it reads the signals
- In the air: the jet's transponder is broadcasting right now. Climbing, cruising, descending or on approach comes from its vertical speed.
- Rough ETA: straight-line distance to the airport you enter divided by current ground speed, plus a few minutes for the approach. Treat it as ±10 min; confirm with the FBO when it matters.
- Likely landed: it was low and close to an airport when the signal stopped. Smaller fields often lose coverage below a few hundred feet, so this is usually a landing.
- Not transmitting: normally parked with the transponder off. A jet using a PIA privacy address cannot be found by tail number at all; ask the operator for its callsign or call the FBO.
- Data comes from free community ADS-B networks (adsb.lol, airplanes.live), which do not hide LADD-blocked jets the way FlightAware and Flightradar24 do. Free feeds allow about 1 request per second, so the list refreshes one tail at a time every 45 seconds.
If the page says it cannot reach the feeds
Make sure api.php sits in the same folder as this page on the server. Opened as a local file, the page calls the feeds directly, which some browsers block.