TFR and NOTAM area
Draws the area a or describes, a circle around packed coordinates or a fix-radial-distance, or a list of points, with its area, bounds, and altitude limits, ready to download as GeoJSON.
Planning and education aid. Not for primary navigation. Full disclaimer
Experimental: not yet fully verified. How results are checked
The area covers 28.24 NM², from 39.51662° to 39.61671° and -122.78966° to -122.66034°.
- Floor
- Ceiling
- Center latitude
- Center longitude
- South edge
- North edge
Provenance
- Computed by
- aviation.airspace.tfr-area 1.0.0, core 0.1.0
- Model
- A circle is 72 points at 5° steps of the geodesic direct problem from the center (Karney 2013); a fix-radial-distance center is the navaid's position carried along radial + variation for the distance. Area by Karney's geodesic polygon area; the GeoJSON ring runs counterclockwise and closes on its first point (RFC 7946)
- Accuracy
- Points exact on WGS 84; the 72-point circle's chords sag under 0.1% of the radius. Check the NOTAM itself: this draws what you enter
- Notes
- 1 shown with the answer
- Cites
- Federal Aviation Administration, Notices to Air Missions (NOTAM), FAA Order JO 7930.2; Internet Engineering Task Force, The GeoJSON Format (RFC 7946)
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: A circle is 72 points at 5° steps of the geodesic direct problem from the center (Karney 2013); a fix-radial-distance center is the navaid's position carried along radial + variation for the distance. Area by Karney's geodesic polygon area; the GeoJSON ring runs counterclockwise and closes on its first point (RFC 7946)
Show your work
Outline
72 geodesic points for a circle, or the entered corners72 points= 72 pointsArea
Karney geodesic polygon area72 points on WGS 84= 28.24 NM²
The same steps an agent gets from the MCP server with explain: true.
Accuracy: Points exact on WGS 84; the 72-point circle's chords sag under 0.1% of the radius. Check the NOTAM itself: this draws what you enter
Worked example: A 3 NM TFR, surface to 3,000 ft MSL. Source: add-practitioner-essentials TFR scenario: a 3 NM geodesic circle, exportable as GeoJSON with its altitude limits. It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.
You enter
- Ceiling
- 3000 FT MSL
- Center
- 393400N1224330W
- Floor
- SFC
- Radius
- 3 NM
You get
- Area
- 28.24 NM²
- Floor
- SFC
- Ceiling
- 3000 ft MSL
- Center latitude
- 39.5666667°
- Center longitude
- -122.725°
- South edge
- 39.51662°
- North edge
- 39.61671°
- West edge
- -122.78966°
- East edge
- -122.66034°
- File name
- tfr-area.geojson
- Media type
- application/geo+json
- GeoJSON
- {"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[-122.72500000000001,39.61670864008062],[-122.73063921465148,39.616518079319675],[-122.73623541933856,39.61594785040312],[-122.74174593423719,39.6150023022747],[-122.74712873720551,39.6136886460782],[-122.75234278615102,39.612016899820254],[-122.75734833369172,39.60999981150851],[-122.76210723164594,39.60765276136904],[-122.7665832229728,39.604993643910625],[-122.77074221889256,39.60204273076034],[-122.77455255904201,39.59882251534437],[-122.77798525266311,39.59535754062779],[-122.78101419898293,39.591674211257086],[-122.78361638511555,39.58780059156776],[-122.7857720600032,39.58376619102588],[-122.7874648831098,39.579601738766065],[-122.7886820467852,39.57533894896844],[-122.78941437143006,39.57101027888296],[-122.78965637280798,39.56664868136148],[-122.7894063010702,39.5622873537939],[-122.78866615127865,39.557959485367775],[-122.78744164543228,39.55369800457695],[-122.78574218621813,39.54953532889808],[-122.78358078292092,39.54550311853091],[-122.78097395013158,39.54163203606289],[-122.77794158009439,39.53795151386802],[-122.7745067897236,39.53448953098737],[-122.77069574350142,39.531272401162056],[-122.76653745364015,39.528324573603086],[-122.76206355905046,39.52566844798248],[-122.75730808480431,39.52332420502176],[-122.75230718391538,39.521309653934836],[-122.7470988633794,39.51964009785536],[-122.74172269652358,39.518328218243354],[-122.73621952380523,39.517383979124645],[-122.73063114427738,39.5168145518693],[-122.72500000000001,39.516624261062915],[-122.71936885572264,39.5168145518693],[-122.71378047619478,39.517383979124645],[-122.70827730347644,39.518328218243354],[-122.70290113662061,39.51964009785536],[-122.69769281608464,39.521309653934836],[-122.69269191519571,39.52332420502176],[-122.68793644094956,39.52566844798248],[-122.68346254635986,39.528324573603086],[-122.6793042564986,39.531272401162056],[-122.67549321027641,39.53448953098737],[-122.67205841990562,39.53795151386802],[-122.66902604986844,39.54163203606289],[-122.6664192170791,39.54550311853091],[-122.66425781378189,39.54953532889808],[-122.66255835456774,39.55369800457695],[-122.66133384872137,39.557959485367775],[-122.66059369892982,39.5622873537939],[-122.66034362719203,39.56664868136148],[-122.66058562856996,39.57101027888296],[-122.66131795321482,39.57533894896844],[-122.66253511689021,39.579601738766065],[-122.66422793999682,39.58376619102588],[-122.66638361488447,39.58780059156776],[-122.66898580101709,39.591674211257086],[-122.6720147473369,39.59535754062779],[-122.67544744095801,39.59882251534437],[-122.67925778110745,39.60204273076034],[-122.68341677702722,39.604993643910625],[-122.68789276835408,39.60765276136904],[-122.6926516663083,39.60999981150851],[-122.697657213849,39.612016899820254],[-122.7028712627945,39.6136886460782],[-122.70825406576283,39.6150023022747],[-122.71376458066146,39.61594785040312],[-122.71936078534854,39.616518079319675],[-122.72500000000001,39.61670864008062]]]},"properties":{"floor":"SFC","ceiling":"3000 ft MSL"}}
Review: Not yet independently reviewed by a flight instructor (CFI).
Last verified: 2026-09-22, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 8 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Notices to Air Missions (NOTAM), FAA Order JO 7930.2, Federal Aviation Administration, JO 7930.2U, effective August 10, 2025. TFR and airspace NOTAM formats: latitude and longitude as degrees, minutes, and seconds with N/S and E/W, fix-radial-distance references, radii in nautical miles, and altitude limits.
- The GeoJSON Format (RFC 7946), Internet Engineering Task Force, RFC 7946. Section 3.1.6 (Polygon, counterclockwise exterior rings) and 3.2 (Feature properties).
Terms
- NOTAM: Notice to Air Missions
- A published notice of something pilots need to know that is not on the charts yet, such as a closed runway, an unlit tower, or a flight restriction. Source: Notices to Air Missions (NOTAM), FAA Order JO 7930.2
- TFR: temporary flight restriction
- Airspace closed to most flights for a time, for example around a fire, a stadium, or a VIP visit, published by NOTAM as a circle or area with a floor and a ceiling. Source: Notices to Air Missions (NOTAM), FAA Order JO 7930.2
Experimental means this tool has not yet met the stable bar: at least 20 golden vectors, differential tests, and an independent worked example.
NOTAM — Notice to Air Missions
A published notice of something pilots need to know that is not on the charts yet, such as a closed runway, an unlit tower, or a flight restriction.
Source: Notices to Air Missions (NOTAM), FAA Order JO 7930.2
TFR — temporary flight restriction
Airspace closed to most flights for a time, for example around a fire, a stadium, or a VIP visit, published by NOTAM as a circle or area with a floor and a ceiling.
Source: Notices to Air Missions (NOTAM), FAA Order JO 7930.2