Flights reconstructed from ADS-B, the position signal modern aircraft broadcast to air traffic. Coverage is strongest across North America and Europe, thinner over oceans, polar regions, and parts of Asia and Africa.

Long-haul flights whose paths cross sparsely-covered areas may appear with an unknown origin or destination, because the receiver network loses sight of them mid-ocean. We mark those unknown rather than guess. Every flight is still counted in the totals; the route-by-route breakdown filters to flights with identified endpoints.