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  2. Height above ground level - Wikipedia

    en.wikipedia.org/wiki/Height_above_ground_level

    In aviation, atmospheric sciences and broadcasting, a height above ground level (AGL [1] or HAGL) is a height measured with respect to the underlying ground surface.This is as opposed to height above mean sea level (AMSL or HAMSL), height above ellipsoid (HAE, as reported by a GPS receiver), or height above average terrain (AAT or HAAT, in broadcast engineering).

  3. Airspace - Wikipedia

    en.wikipedia.org/wiki/Airspace

    Class A airspace is generally the airspace from 18,000 feet (~3.4 miles, 5.5 km) mean sea level (MSL) up to and including flight level (FL) 600 (~11.4 miles, 18.3 km), including the airspace overlying the waters within 12 nautical miles (NM) (~13.8 miles, 22.2 km) of the coast of the 48 contiguous states and Alaska. Unless otherwise authorized ...

  4. Ordnance datum - Wikipedia

    en.wikipedia.org/wiki/Ordnance_datum

    An ordnance datum (OD) is a vertical datum used by an ordnance survey as the basis for deriving altitudes on maps. A spot height may be expressed as above ordnance datum (AOD). Usually mean sea level (MSL) at a particular place is used for the datum.

  5. DTED - Wikipedia

    en.wikipedia.org/wiki/DTED

    DTED (or Digital Terrain Elevation Data) is a standard of digital datasets which consists of a matrix of terrain elevation values, i.e., a Digital Elevation Model.This standard was originally developed in the 1970s to support aircraft radar simulation and prediction.

  6. Airspace class - Wikipedia

    en.wikipedia.org/wiki/Airspace_class

    Class E airspace exists above Class G surface areas from 14,500 ft (4,400 m) MSL to 18,000 ft (5,500 m) MSL. Federal airways from 1,200 ft (370 m) AGL to 18,000 ft (5,500 m) MSL within 4 miles (6 km) of the centerline of the airway is designated Class E airspace. Airspace at any altitude over FL600 (60,000 ft; 18,300 m) (the ceiling of Class A ...

  7. Chart datum - Wikipedia

    en.wikipedia.org/wiki/Chart_datum

    In non-tidal areas, e.g. the Baltic Sea, mean sea level (MSL) is used. [2] A chart datum is a type of vertical datum and must not be confused with the horizontal datum for the chart. Definitions

  8. Geodetic coordinates - Wikipedia

    en.wikipedia.org/wiki/Geodetic_coordinates

    Geodetic latitude and geocentric latitude have different definitions. Geodetic latitude is defined as the angle between the equatorial plane and the surface normal at a point on the ellipsoid, whereas geocentric latitude is defined as the angle between the equatorial plane and a radial line connecting the centre of the ellipsoid to a point on the surface (see figure).

  9. Vertical datum - Wikipedia

    en.wikipedia.org/wiki/Vertical_datum

    Vertical datums in Europe. In geodesy, surveying, hydrography and navigation, vertical datum or altimetric datum is a reference coordinate surface used for vertical positions, such as the elevations of Earth-bound features (terrain, bathymetry, water level, and built structures) and altitudes of satellite orbits and in aviation.