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The North American Vertical Datum of 1988 (NAVD 88) is the vertical datum for orthometric heights established for vertical control surveying in the United States based upon the General Adjustment of the North American Datum of 1988. [1] It superseded the National Geodetic Vertical Datum of 1929 (NGVD 29), [2] previously known as the Sea Level ...
Vertical measurements, based on distances above or below Mean High Water (MHW), are calculated using the North American Vertical Datum of 1988 (NAVD 88). [ 1 ] NAD 83, along with NAVD 88, is set to be replaced with a new GPS - and gravimetric geoid model-based geometric reference frame and geopotential datum, potentially in 2025 .
The system is based on the datums NAD 83 and NAVD 88. [3] In 2024 or 2025, [needs update] the NSRS will be modernized with a focus on Global Navigation Satellite Systems (GNSS) and geoid use. It will use the following four frames of reference, each representing a tectonic plate: [4] [5] North American Terrestrial Reference Frame of 2022 (NATRF2022)
An American Airlines jet and an Army helicopter collided over Washington, D.C., Wednesday night. All 67 people aboard the aircraft are presumed dead.
The last crash of a U.S. airliner was the Colgan Air accident in February 2009, which killed 49 people on the plane and one on the ground during a snowstorm near Buffalo, New York.
On Friday, the U.S. Army released information on the crew of the Black Hawk helicopter that collided with a passenger jet near Reagan National Airport in Arlington, Virginia.
NGVD 29: Sea Level Datum 1929: OSGB36: Ordnance Survey Great Britain 1936: SK-42: Systema Koordinat 1942 goda: ED50: European Datum 1950: SAD69: South American Datum 1969: GRS 80: Geodetic Reference System 1980: ISO 6709: Geographic point coord. 1983: NAD 83: North American Datum 1983: WGS 84: World Geodetic System 1984: NAVD 88: N. American ...
This list of accidents and incidents involving commercial aircraft includes notable events that have a corresponding Wikipedia article. Entries in this list involve passenger or cargo aircraft that are operating commercially and meet this list's size criteria—passenger aircraft with a seating capacity of at least 10 passengers, or commercial cargo aircraft of at least 20,000 lb (9,100 kg).