@squawk/airspace

  @squawk/airspace

Pure logic library for querying US airspace geometry. Given a position and altitude, returns all applicable airspace designations. Contains no bundled data - accepts a GeoJSON dataset at initialization. For zero-config use, pair with @squawk/airspace-data.

Part of the @squawk aviation library suite. See all packages on npm.

Coverage

• Class B, C, D, and E controlled airspace (E2 through E7 subtypes)
• Special Use Airspace: MOAs, restricted, prohibited, warning, alert, and national security areas

Usage

import { usBundledAirspace } from '@squawk/airspace-data';
import { createAirspaceResolver } from '@squawk/airspace';

const resolver = createAirspaceResolver({ data: usBundledAirspace });

// Query a position and altitude
const overhead = resolver.query({ lat: 33.9425, lon: -118.4081, altitudeFt: 3000 });

for (const f of overhead) {
  console.log(f.type, f.name, f.identifier);
}

// Get every shell associated with an airport (for drawing the full wedding cake)
const laxShells = resolver.byAirport('LAX');

Consumers who have their own GeoJSON airspace data can use this package standalone:

import { createAirspaceResolver } from '@squawk/airspace';

const resolver = createAirspaceResolver({ data: myGeoJson });

How it works

createAirspaceResolver parses the GeoJSON FeatureCollection at initialization and returns a resolver object with two methods:

• query(AirspaceQuery) - returns features containing the given position and altitude, via a ray casting point-in-polygon test combined with a vertical floor/ceiling comparison.
• byAirport(identifier, types?) - returns every feature whose identifier matches (case-insensitive). For Class B/C/D/E2 this groups all sectors of the airspace around a given airport regardless of the point of interest.

All matching features are returned as AirspaceFeature objects (from @squawk/types), including the full polygon boundary coordinates.

AGL altitude handling

Some airspace features have floor or ceiling bounds referenced to AGL (above ground level) rather than MSL. Converting AGL to MSL requires terrain elevation data that this library does not include.

The resolver handles AGL bounds conservatively: when it cannot determine the MSL equivalent, it includes the feature rather than silently excluding it. This means the resolver may return features whose AGL bounds do not actually contain the queried altitude.

Consumers can inspect the reference field on the returned AltitudeBound objects and apply their own terrain lookup if needed:

for (const f of features) {
  if (f.floor.reference === 'AGL') {
    // This feature's floor is AGL - apply terrain data if available
  }
}

API

createAirspaceResolver(options)

Creates a resolver from a GeoJSON dataset.

Parameters:

• options.data - a GeoJSON FeatureCollection with airspace features

Returns: AirspaceResolver - an object exposing query(AirspaceQuery) and byAirport(identifier, types?) methods.

AirspaceQuery

Property	Type	Description
lat	number	Latitude in decimal degrees (WGS84)
lon	number	Longitude in decimal degrees (WGS84)
altitudeFt	number	Altitude in feet MSL
types	ReadonlySet<AirspaceType>	Optional. When provided, only features of these types are returned

// Only query tower-controlled airspace (exclude Class E and SUA)
const controlled = resolver.query({
  lat: 33.9425,
  lon: -118.4081,
  altitudeFt: 3000,
  types: new Set(['CLASS_B', 'CLASS_C', 'CLASS_D']),
});

resolver.byAirport(identifier, types?)

Returns every airspace feature whose identifier property matches. For Class B/C/D/E2 this is the associated airport's FAA location identifier (e.g. "JFK" for the NY Class B). For Special Use Airspace this is the NASR designator (e.g. "R-2508"). Lookup is case-insensitive. ICAO-prefixed codes like "KJFK" will not match - resolve to an FAA ID first via @squawk/airports.

// Every sector of the NY Class B around JFK, with full polygon boundaries
const jfkShells = resolver.byAirport('JFK');

// Only the Class D for a towered field
const safClassD = resolver.byAirport('SAF', new Set(['CLASS_D']));