User guide

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ellipsoid or the arc of an ellipsoid that most closely represents the area being described. In addition,
the datum is centered at a specific location (the datum origin). A datum may describe a small
part of the earth, such as California or Iceland or may describe the entire earth, such as WGS84,
depending on which ellipsoid or ellipsoidal arc is selected.
Since datums use different ellipsoids and origins, the LAT/LON coordinates of the same position
differs from one datum to another. The difference may be slight or great, depending on the datums
involved, but will affect the apparent accuracy of the positioning information provided by a GPS
receiver. GPS (and all of the EKP-IV cartridges) use the WGS84 datum, which is the model of the
earth that is the closest possible average of the planet as a whole. Your chart datum is usually found
in the legend. If the datum is not WGS84 means that position coordinates determined with the
EKP-IV may not appear to agree with coordinates determined from a printed chart.
APPENDIX C - ICAO CODES
The EKP-IV Database of airports is drawn from the system of ICAO (International Civil Aviation
Organization) identifiers. Unlike the IATA (International Airline Transport Association) identifiers
seen on charts and luggage tags, the ICAO codes minimize the possibility of duplicate identifiers
and allow pilots to identify an airport’s region and nearby large city. ICAO codes for international
airports use a 2-character identifier for the region, followed by 1 character that identifies the
airport’s general area, then 1 character of the airport.
For example, the ICAO code for Melbourne, Australia is YMML (IATA code MEL). All of Victoria and
Tasmania are in the YM region and the international airports in the Melbourne area start with “M”.
Therefore, Melbourne International Airport is YMML and the nearby Moorabbin Airport is YMMB.
In North America, the region containing Los Angeles begins with a “K” and the airport identifier of
L.A. International Airport is “KLAX”. Merrill Field in Anchorage, Alaska, begins with region code PA;
its identifier is PAMR.
The ICAO codes for the hundreds of smaller airports around the world whose names include
numbers are not preceded by a region prefix. For example, Barrie Executive Airport in Barrie,
Ontario, Canada is NA3.
The following pages contain maps and a table of ICAO codes. The map of the continental U.S.
contains the 2-character codes that identify the U.S. (“K”) and the area (the following number). The
world map shows the region codes only. The ICAO codes in the table are 2-character codes; like
“K2” and similar ICAO codes for the U.S., these codes identify both region (the first character) and
a geographical area within the region (the second character). Where necessary, the geographical
area or nearest nation is also included in parentheses. Please note that these regions and nations
are provided for loca-tion only and do not necessarily indicate possession by the nation indicated.
All areas are as described by the standard ARINC 424 format.
A list of worldwide ICAO codes is also available in book form from the International Civil Aviation
Organization. Ask for ICAO Location Indicators, document number 7910/70.
Document Sales Unit - International Civil Aviation Organization
1000 Sherbrooke Street West, Suite 400 - Montreal, Quebec, Canada
H3A 2R2 Tel.: [phone].