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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
ACARS reports are received via ARINC
and the Air Force Weather Agency (AFWA).
Data from the former is stored in the observational database as BUFR
b004/xx004 and is the primary source for ACARS data
used within the NCEP models. Conversely, ACARS data that is received
from AFWA 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 ARINC.
AMDAR reports, on the other hand, are always fully assimilated into the NCEP
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/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
aircft, as well as in most
- 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
Within the initial 48-hour period, the airlines allow use of the data by
global numerical modeling centers such as NCEP, AFWA, 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
email@example.com before making the
- 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.