Where the numbers come from, how we compute them, and what they mean.
Everything on routeloads comes from one place: the U.S. Department of Transportation's Bureau of Transportation Statistics (BTS). It's public-domain data that every U.S. carrier is legally required to file — actual seats flown, actual passengers carried, actual fares sold. No logins, no estimates, no scraping. We just take the government's own numbers and make them readable.
Monthly seats, passengers, and departures on every nonstop segment a carrier flies. This is the source of load factor and capacity — how many seats went out and how many people were in them.
U.S. DOT BTS · T-100A 10% sample of all airline tickets sold, giving average round-trip fares by origin–destination market. This is the source of the average fare you see on each route.
U.S. DOT BTS · DB1BReported on-time arrival rates for nonstop operations by the larger U.S. carriers. This is the source of the on-time rate — the share of flights that landed on schedule.
U.S. DOT BTS · OTPload factor = passengers ÷ seats over the trailing window. It's the single best answer to "how full does this route fly?" We show it as a percentage and color it on a green→red scale — and here, greener means emptier: a low load factor is the open seat, the upgrade, the cheaper standby. A route running near 100% is packed.
This is the DB1B average origin-and-destination market fare, round-trip. One important caveat: DB1B is a 10% ticket sample, and it's an origin–destination figure rather than a single-segment price — so a connecting passenger's whole journey is attributed to the market, not one leg. Treat the average fare as a market signal — a sense of what a route typically costs — not a live quote for a specific flight.
The share of that route's nonstop operations that arrived within the DOT's on-time threshold. Higher is better, so this scale runs the other way: greener means more reliable, red means a route with a history of running late.
open seats = seats − passengers — roughly how many empty seats a typical departure on that route carries. It's the same story as load factor, told in raw seats instead of a percentage: a useful gut-check for how much slack a route actually has.
The data is monthly, and right now it spans 2021 through 2026 — roughly 4,460 mapped routes across 1,700+ airports. Because carriers file with the DOT on a lag, the latest complete month trails the calendar by a few months. That's normal for BTS data: it's the price of using filed, audited numbers instead of guesses. When a fresh month is published, it flows straight through.
This is historical monthly data, not live availability — and it's worth being clear about the edges:
That's the whole recipe — public DOT filings, a few honest formulas, and a color scale where greener means emptier, cheaper, and more reliable. Now go put it to work: