Formation flights: aircraft flying together in the data

Military aircraft, airshow teams and photo flights sometimes fly in formation, a few hundred feet or less apart and matching speed and heading. When both aircraft broadcast their own ADS-B positions, the pair shows up in the data as two tracks that move together.

The site publishes a pair only when both aircraft broadcast their own ADS-B positions. Positions estimated by multilateration are too uncertain at this spacing, and a pair that relies on positions relayed by ground stations is held for review. The two must stay within 0.5 nautical miles and 400 ft of each other, with tracks within 20 degrees and ground speeds within 25 knots, for at least two minutes. They must be at 3,000 ft or higher, or at 1,500 ft and well away from a runway, so that traffic around an airport does not count. A tanker type in the pair, or a glider climbing behind a towplane, adds a tag that says what the shape looks like.

Two aircraft close together on a map are not always flying in formation. One transponder can appear under two addresses, and parallel approaches can look similar for a minute or two. The data cannot show whether the crews arranged to fly together, and a tanker in the pair does not prove that any fuel was transferred. Federal rules allow formation flight only by arrangement with the pilot in command of each aircraft.