Methodology — how LayoverDB decides

Data rule: UNKNOWN > WRONG

Every factual field in the dataset is optional. If it cannot be verified against an official source it stays null and renders as Unknown. Facility pages are only generated when at least one verified location exists. The checker returns insufficient data rather than inventing a transfer time.

How the layover checker computes a verdict

  1. Total layover. Departure time minus arrival time, in airport local time. A departure earlier in the day than arrival is treated as an overnight connection crossing midnight (+24 h).
  2. Transfer time. The officially published range for the terminal pair. Same terminal: 0. No verified data: the engine refuses to estimate.
  3. Buffers. +30 minutes to re-clear security when your route leaves the secured area (landside transfer or international→domestic); +60 minutes for immigration and customs when entering the country. These are heuristics and are always shown, never hidden — including where the number came from: site default or an airport-specific override (see below).
  4. Usable time = total − transfer (upper bound) − buffers.
  5. Verdict: ≥60 min usable → likely comfortable; 30–59 → tight; <30 → very tight; missing inputs → insufficient data.

Buffers: site default or airport override

The +30/+60 minute buffers are heuristics, applied identically to every airport unless the dataset says otherwise. An airport can carry buffer_overrides in data/airports/<IATA>.json when an official source states a time — globally for that airport and/or per connection type (e.g. only for international→domestic). Every buffer the checker applies is labelled with its origin — site default or <IATA> override — on the layover calculator result and in the reasoning list, so a number that is not a heuristic can never pass as one.

Current dataset: no airport overrides the defaults — every airport uses +30 / +60.

Facility reachability states

  • Reachable — airside-compatible path exists (same terminal, or a verified airside transfer).
  • Possibly reachable — landside facility or landside transfer: you can get there, but immigration and security re-entry may apply depending on your itinerary and nationality.
  • Not reachable — airside facility in a terminal you cannot return to after a landside onward transfer.
  • Unknown — the official source does not document the zone or the path.

What this is not

The checker's output is an informational estimate, not a guarantee. Flight delays, queue lengths, gate changes and airline minimum connection times all live outside our data. Visa and entry questions are answered only by links to government sources — we never summarize them into advice.