PPRuNe Forums - View Single Post - Jet goes down on its way to Medellin, Colombia
Old 2nd Dec 2016, 21:21
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DaveReidUK
 
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Originally Posted by peekay4
1nm error is well outside the limits specified for ADS-B. The position limit is 0.05nm with an integrity bubble of 0.2nm. These requirements can be tough to meet using legacy inertial or RNAV sources, which is why most ADS-B retrofits will include GPS instead.
Don't confuse ADS-B with specific implementations of it (e.g. NextGen, Hudson Bay, etc).

ADS-B doesn't have specific limits - the spec accommodates a wide range of accuracy and integrity levels, which is why every position transmission includes a parameter (NUCp) that identifies the level that applies to the data.

Specific ADS-B implementations can require a minimum NUCp - the Hudson Bay ADS-B-mandatory airspace, for example, requires a minumum NUCp of 5, for example, so inertial-based ADS-B won't normally meet that criterion (but it still satisfies the ADS-B spec).

Thr LAMIA RJ85 had ADS-B, but would not have been allowed to fly in US airspace under NextGen rules.
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