How this works

Most aircraft broadcast their position, height and speed several times a second, and volunteers around the world pick those signals up with small radio receivers and share them through adsb.lol. Our flight log checks that data for the sky over Guthrie every twelve to twenty seconds, around the clock.

A flight is listed once it has gone, at the moment it came closest to downtown, if that was within five miles. Heights are above sea level, the way pilots report them; the ground around Guthrie is roughly 1,000 feet above sea level, so for low aircraft we also give an estimate of the height above the ground.

The tail number is the registration painted on the aircraft, which it broadcasts along with its position, and which anyone can look up in the Federal Aviation Administration’s public registry. Select one to see every flight that aircraft has made over Guthrie in the past week. Aircraft that don’t broadcast their position don’t appear at all, and a few are seen only by radar and carry no identification — most military flights broadcast no tail number either.

Emergency codes. A pilot can set the transponder to say something is wrong: 7700 for an emergency, 7600 for a lost radio, 7500 for unlawful interference, and the aircraft can also broadcast low fuel. When one near Guthrie does so for at least two separate position reports, its flight is marked, and our newsroom is told within about a minute. The mark says what was broadcast, not that anything went wrong — codes are sometimes set by mistake, and an emergency can be a sick passenger. It appears once the flight has been logged, not while it is happening. Air ambulances’ medical-priority flag is never recorded: it is not an emergency with the aircraft, and a log of it would be a log of other people’s medical emergencies.

Which way the traffic comes. Downtown sits on runway 16’s centre line, a mile and a half north of it. An aircraft landing on 16 comes in over downtown; one taking off on 34 climbs out over it. The line saying which is happening now follows what the last few aircraft to land actually did; only when nobody has landed lately does it go by the wind, from the airport’s own weather station, and then it says the wind favours a runway, because that is a prediction. Heights over downtown are measured from downtown’s own ground, 983 feet above sea level by the U.S. Geological Survey’s elevation data — 85 feet lower than the runway, which is what heights above the ground elsewhere on these pages are measured from.

Where a flight was going is the one line here we did not watch happen. An aircraft broadcasts a flight number, never a destination, so for airline flights we look the number up in the published schedules — and then check that answer against the aircraft itself. A flight number is reused and re-routed from season to season, so the schedule can easily describe a different journey from the one that crossed the county. We keep it only when the airport it names lies ahead of the heading the aircraft was actually on, and drop it when it does not. Roughly half the flights over Guthrie carry a flight number at all; private aircraft have no published schedule and are never given one here. A route is where an aircraft was booked to go, not proof of where it landed.

Flight data from adsb.lol contributors, available under the Open Database License. This page and the airport log are derived from it by the method described above. Airline schedules and airport names from the Virtual Radar Server standing-data collection, public domain.