Runway Intelligence Methodology

• Active — a runway the tower states is in use: from the tower's TFDM surface system (structured data, via FAA SWIM) where the airport has it, otherwise from the D-ATIS broadcast text. Active is never inferred from wind.
• Favored — the end of a runway with more headwind in the current METAR. Pure arithmetic, recomputed every minute; no knowledge of traffic, noise abatement or what ATC is doing.
• Predicted — the ATIS Alerts estimate of the runway most likely in use at future hours, from the TAF wind and runway geometry. Labelled with a confidence band; never an assignment.
• Recorded use — hours during which the facility stated each end, from every change of the TFDM configuration or the D-ATIS since we started listening.
• Wind-favored history — at airports without a stated-runway source, the share of hours each end would have had the most headwind. Always labelled as wind-inferred.

• Tower runway configuration, closures, demand and traffic-management restrictions: FAA SWIM Cloud Distribution Service, TFDM (Terminal Flight Data Manager) Airport Information and Traffic Management Restrictions services, at the towers that publish them (about 36 in September 2026). Configuration lists come from per-runway rates; a runway with a zero rate for a role is not used for that role.
• Runway visual range and runway-light settings: FAA SWIM STDDS Airport Data (APDS), about 130 airports. Values are in hundreds of feet with 6,000 ft the reportable maximum; a reading of zero means the sensor is off, not zero visibility.
• D-ATIS text: the community relay at atis.info of the FAA digital ATIS, polled every five minutes and every minute on the page; parsed with an open, tested role-aware parser; the broadcast text is always shown.
• METAR and TAF: aviationweather.gov. Wind components use TRUE runway headings against TRUE METAR wind; magnetic headings are shown for orientation only.
• Runway record: OurAirports / FAA runway data (length, width, surface, lighting, headings). Declared distances, lighting systems and ILS types are not yet included.
• Climatology: Iowa Environmental Mesonet ASOS archive, 2005–2025, one observation per clock hour, the same archive and hourly method as the Flying Weather Index.
• Instrument approaches: the FAA d-TPP chart index for the current charting cycle; plates link to aeronav.faa.gov and no minimums are reproduced.

Every change of the tower's configuration (TFDM) or of the D-ATIS opens a new configuration interval and closes the previous one. Use over the last 30 days is the duration-weighted share of hours in which each end was stated for arrivals and for departures, split by wind sector (eight 45° sectors from the wind reported when the interval began) and by airport-local time of day. TFDM intervals start at the tower's own start time, so the history begins before we started listening; D-ATIS intervals start at the broadcast time. A station whose broadcast goes silent or stale is credited only one ATIS cycle past its last broadcast. Where a tower has TFDM the page uses the TFDM stream; the two streams are never mixed.

For each forecast hour the TAF wind is resolved against every open runway end. Each end is scored by headwind, minus a crosswind penalty, minus a penalty for any tailwind above five knots, with the longest runway breaking ties. Confidence starts at 50, rises six points per knot of headwind margin over the runner-up, and falls with forecast distance, gusts, TEMPO groups and a TAF older than six hours, clamped between 20 and 95. When the tower has stated a configuration, the “Now” row shows that instead and says so. The model does not know about noise abatement, flow programs or construction unless the D-ATIS states them.

For every runway end, each hourly observation with a steady wind direction is resolved into headwind and crosswind components against the end's true heading. The page reports the share of hours with a headwind, tailwind above 5, 10 and 15 kt, crosswind above 5 to 25 kt, mean, median, 90th and 95th percentiles, the strongest and calmest months, and the same by month, time of day and wind sector. Calm and variable-direction hours are excluded from the wind denominators and reported separately. Today's runway geometry is applied to all years, so a runway renumbered or built during the period carries the current heading throughout. A headwind requires at least 0.01 kt of component, so an exactly perpendicular wind counts for neither end.

• The FAA runway record marking a runway closed wins over everything.
• A tower TFDM closure record for a runway the current configuration does not use reads CLOSED (TOWER TFDM); one for a runway the configuration still uses reads CLOSURE ON RECORD, because the closure may be partial or the record may lag.
• A D-ATIS closure reads CLOSED (D-ATIS); a broadcast restriction or equipment outage naming the runway reads RESTRICTED or EQUIPMENT OUTAGE with the clause quoted verbatim.
• NO CLOSURE REPORTED requires a tower feed or a D-ATIS broadcast fresh within three hours; a stale feed reads STATUS UNKNOWN, and an airport with neither source reads NOT MONITORED. No page ever reads “open” without a live source, and runway NOTAMs are not monitored yet.

SWIM content is received under the FAA SWIM Cloud Distribution Service terms for non-operational use; ATIS Alerts is not an FAA product and nothing shown here is FAA data or a clearance. Recorded use begins the day we began listening (September 18, 2026 for D-ATIS; earlier for TFDM where the tower's start time predates it). Runway NOTAMs, declared distances and lighting systems are scheduled for a later phase. Always verify runway assignments, closures and weather with official sources before flight.

Questions or corrections: the contact page. See also the about page for how the rest of the site is built.