ARP Lookup — Tool Guide

Who It's For & When to Use It

Airport planners who need the ARP — fast and citable — while writing an ALP narrative, setting up a coordinate conversion, georeferencing a base map, or sanity-checking a survey deliverable. Use it whenever you would otherwise open the Chart Supplement or dig through reference data just to grab a latitude, longitude, or field elevation. Because the result carries the data source and NASR cycle date, it's also the right starting point for any workflow that has to be defensible — the coordinates you paste into a report come with their citation attached.

The tool also acts as a hub: once an airport resolves, jump links carry the identifier (and coordinates) straight into State Plane zone detection, Declared Distance, Runway Designation, and ALP Data Tables — so a single lookup feeds the rest of your session.

How to Use It

1. Enter an identifier. Type an FAA LID or ICAO code into the field (placeholder “FAA identifier (e.g. KDEN, KLAX)”) and press Enter or click Look Up. Input is forced to uppercase as you type. A bare 3-letter code is auto-prefixed with K — for example DEN becomes KDEN — and the normalized identifier is written back into the field. Non-K-prefixable codes such as 06C are accepted as entered.
2. Watch the status line. While the lookup runs, a spinner and “Looking up …” message appear below the search row. The URL is also updated with ?id= so the result is shareable and bookmarkable.
3. Acknowledge the fallback banner if it appears. If the airport resolves only from community data, a bordered warning banner appears with the source title and explanation and two buttons: Continue with OurAirports data or Stop. No coordinates are rendered until you choose. Continue reveals the result; Stop clears it and tells you to enter a US airport for authoritative FAA NASR data. Authoritative NASR results skip the banner entirely.
4. Read the airport header. The result shows the airport name with a data-source badge beside it (FAA NASR vs. the community fallback), then the identifier and municipality/state. Authoritative NASR hits with coordinates also show a checkmarked note — “ARP surveyed per FAA NASR (cycle …)” — documenting exactly which 28-day cycle the coordinates came from.
5. Read and copy the coordinates. Latitude and longitude appear as cards in decimal degrees (six places) with the DMS equivalent directly below each value. Each card has a Copy button (DD value) and a Copy DMS button.
6. Read the remaining facts. Cards show field Elevation in feet MSL, the State, and — when the data source provides them — Magnetic Variation (degrees E/W) and the full set of Identifiers (ICAO / FAA / Local / IATA). Cards for fields the source doesn't carry are hidden.
7. Copy the full block for a citation. Copy all (with source & cycle) puts every field — name, identifier, location, DD and DMS coordinates, elevation, mag var, state, identifiers, the NAD83 datum line, and the data source plus cycle date — on the clipboard as a ready-to-paste, trail-backed block.
8. Carry the airport into another tool. Under Use this airport in, jump links open Detect State Plane zone (carries ?id= plus ?lat=&lon=), Declared Distance, Runway Designation, and ALP Data Tables (each carries ?id=).

Key Features

• K-prefix auto-add — bare 3-letter codes (DEN) are normalized to the ICAO form (KDEN) and reflected back into the field, so you don't have to remember the leading K.
• Data-source badge + NASR cycle chip — every result is labeled FAA NASR (authoritative, with cycle date) or the community fallback, beside the airport name.
• Mandatory continue/stop fallback banner — non-authoritative data is never shown silently; you must acknowledge it before any coordinates render.
• Loading state — a spinner and status message confirm the lookup is in flight.
• Copy affordances — per-field Copy (DD) and Copy DMS buttons, plus a Copy-all block with source and cycle for a defensible paste.
• NAD83 datum line — a standing disclaimer states the published datum and ARP precision so you cite the right basis.
• Cross-tool jump links — hand off the identifier (and coordinates) to State Plane, Declared Distance, Runway Designation, and ALP Data Tables.
• ?id= deep-link — opening the tool with ?id=KDEN auto-runs the lookup, and every lookup updates the URL so results are shareable.

FAA References

• FAA NASR 28-day subscription — authoritative source for US airport, ARP, elevation, and identifier data; every NASR-served result carries its cycle date so the citation is trail-backed to a specific 28-day cycle.
• OurAirports community data — non-authoritative fallback, used only when NASR does not cover a facility (NASR is US-only) or is unreachable. It is community-maintained and must be acknowledged via the continue/stop banner; the data-source badge keeps it from ever being presented as authoritative.
• NAD83 datum — ARP coordinates are referenced to NAD83 as published by the FAA. Published ARP precision is to the nearest second of arc. The datum line is shown with every result and included in the copy-all block.

Limitations & Disclaimers

AvPlot is technical planning production support — accurate enough for design reports, planning studies, and ALP narratives. It is not a replacement for stamped engineering or construction documents.

• NASR is US-only. Facilities outside NASR coverage are served from community data behind the continue/stop banner and labeled as such — treat those results as reference, not authority.
• The ARP is the approximate weighted centroid of the usable landing surfaces, and published precision is only to the nearest second of arc — it is not a survey monument.
• Verify safety-critical coordinates against the official source document before use in surveys, instrument procedure work, or official submittals.
• Magnetic variation and the extended identifier set appear only when the active data source provides them; absence in a result does not mean the value doesn't exist.

Related Tools

• State Plane Zone Lookup — the “Detect State Plane zone” jump link hands off the identifier and ARP coordinates to find the SPCS83 zone before converting to grid coordinates.
• Declared Distance Calculator — the Declared Distance jump link opens this tool with the airport preloaded.
• Runway Designation Calculator — the Runway Designation jump link carries the identifier across.
• ARP Centroid Calculator — compute a proposed ARP from runway-end coordinates per the FAA weighted-centroid method when no published ARP exists.
• Runway Linework Generator — build CAD-ready runway and surface linework anchored to real-world coordinates (guide).

Tips & Best Practices

• Use Copy all (with source & cycle) when pasting into an ALP narrative or planning study — it carries the NAD83 datum and the NASR cycle date, so the value lands already cited.
• Confirm the data-source badge reads FAA NASR before treating coordinates as authoritative. A community-fallback result is fine as a reference but should be independently verified.
• Bookmark or share the ?id= URL — reopening it re-runs the lookup automatically, so a teammate sees the same airport without retyping.
• Don't add the leading K yourself — type the 3-letter code and let the auto-prefix normalize it; the field shows you exactly what was queried.
• When you need grid coordinates, follow the Detect State Plane zone link first — it carries the ARP latitude and longitude with it, so the zone resolves without re-entry.