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NCEP Home > NCO Home > Systems Integration Branch > NCEP Restricted Data > ACARS and AMDAR Data


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ACARS (Aircraft Communications Addressing and Reporting System) and AMDAR (Aircraft Meteorological Data Relay) are observing systems which provide reports from commercial aircraft during flight. The participating airlines retain a proprietary interest in their data and therefore set the rules regarding to whom and how it may be redistributed.

ACARS reports are received via Rockwell Collins' ARINCDirect and the Air Force's 557th Weather Wing (557WW). Data from the former is stored in the observational database as BUFR type/subtype b004/xx004 and is the primary source for ACARS data used within the NCEP models. Conversely, ACARS data that is received from 557WW is stored in the observational database as BUFR type/subtype b004/xx007 and is only dumped and assimilated into the NCEP models if/when an extended outage occurs which affects the primary feed of data from ARINCDirect.

AMDAR reports, on the other hand, are always fully assimilated into the NCEP models. They are received via several different sources, although a large majority are provided by European airlines and are therefore received via the UK Met Office (UKMO). AMDAR data is stored in the observational database as BUFR type/subtype b004/xx003, b004/xx006 or b004/xx009, depending upon the source and/or code form in which it was received.

In addition to each of the above database files, ACARS/AMDAR data is also present in model dump files containing the names aircar and aircft, as well as in most PREPBUFR files.

The restriction(s):

  • ACARS/AMDAR data is restricted in that it cannot be made available to the general public until 48 hours have elapsed from the observation time of the data, and after which time it can then be made freely available without restriction. Within the initial 48-hour period, the airlines allow use of the data by global numerical modeling centers such as NCEP, 557WW, FNMOC, UKMO, ECMWF, etc., as well as to other official agencies engaged in operational forecasting or related meteorological research that is considered to be of likely benefit to the airlines providing the data. However, the data cannot be made available to others within this 48-hour period, especially to commercial entities who would use it to create products for sale to the participating airlines.

Obligations of users:

  • Users of this data may redistribute it only to recipients within agencies of the U.S. government during the first 48 hours after the observation time of the data. Before doing so, the user must complete the "inform and acknowledge" procedure with the intended recipient as described on the previous page. A template is provided for this purpose which may be cut-and-pasted into an e-mail from the user to the intended recipient. Once the reply acknowledgement is received from the recipient, the user should then forward a copy of this acknowledgement to before making the redistribution.
  • ACARS/AMDAR data is exchanged operationally with other eligible global processing centers under the auspices of the WMO Global Telecommunications System. In the unlikely event that a representative from a foreign center should inquire about receiving such data in real-time (i.e. within the initial 48-hour period) directly through a user at NCEP, the user should refer the inquiry to NWS/TOC for assistance.

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Page last modified: Thursday, 18-May-2006 21:49:40 UTC