From: lhe@sics.se (Lars-Henrik Eriksson)
Subject: Re: Trimble FlightMate Database
Organization: Swedish Institute of Computer Science, Kista
Date: Thu, 1 Oct 1992 08:17:49 GMT

In article <BvEwrJ.9uw@fiu.edu> ege@blitz.fiu.edu (Dr. Raimund K. Ege) writes:
   I tried to look up some airports in other countries (MYNN is Nassau, etc)
   but could not find airports in Germany. Does anybody know, which prefix
   is used for Germany ? FRA (for Frankfurt) is used by airlines (at least
   that's what they use for a luggage tag!), which is not listed in the
   FlightMate's database, nor is DFRA.

Frankfurt is EDDF. How come? Well, ICAO four character "location
indicators" are constructed like this:

The first character identifies the "AFTN routing area". AFTN is the
global telecommunications network used for ATC, aeronatical
information and MET purposes (flight plan messages, notams, airport
forecasts etc).

The conterminous (?) U.S. is region "K". Northern Europe is region
"E". Note that this letter is not a country identifier. E.g.
Anchorage has location indicator PANC, which begins with "P". "P" is
north Pacific, I think.

Some AFTN routing areas fall entirely within a single country ("K" is
in the U.S. and "U" is in the former USSR). In that case that country
is free to allocate the remaining three characters any way it likes.
The U.S. has chosen to use the three-letter airport identifier as the
remaining three letters. In the former USSR another scheme based on
geographical hierarchies is used.

If there are several countries in the routing area, the second
character identifies the particular country. In the case of northern
Europe, we have D = (west) Germany. This is the reason why all
three-letter indentifers of Canadian airports begin with Y (at least
for international airports): Canada is in routing area "C" and has
country code "Y" (perhaps "X" and "Z" also...). I belive all
three-letter identifiers in Alaska begin with "A", for the same
reason. Alaska is in routing area "P" and has country code "A".

The third and fourth letters are assigned by the countries themselves.
ICAO recommends that when the country has several AFTN switching
centres, the third letter should identify that centre the airport is
connected to. Some countries (e.g. Sweden) follow that recommendation,
but most do not.  Germany has chosen "DF" as the final letters for
Frankfurt, so we get "EDDF".

As you can guess from the above, ICAO location indicators are really
telecommunication addresses, thus not only airports have location
indicators. ACCs (corresponding to U.S. "centers") may have location
indicators different from that of the airport they are located on,
e.g. ESSA - Stockholm/Arlanda Airport, ESOS - Stockholm ACC. Various
organisations not directly related to actual air operations mat also
have location indicators. In Sweden you can find "ESKL" - Civil
Aviation Administration central office. "ESWI" - National
meteorological and hydrological institute. "ESSS" - AFTN switching
centre in Stockholm.

There are actually four more letters that are used for subaddressing,
but I won't bore you with these now.

ICAO - International Civil Aviation Organisation
ACC - Area Control Centre
AFTN - Aeronautical Fixed Telecommunications Network
--
Lars-Henrik Eriksson                            Internet: lhe@sics.se
Swedish Institute of Computer Science           Phone (intn'l): +46 8 752 15 09
Box 1263                                        Telefon (nat'l): 08 - 752 15 09
S-164 28  KISTA, SWEDEN                         Fax: +46 8 751 72 30