WMO U.S. STATION NAME STATION STATION NUMBER ID 723080 ORF NORFOLKINTERNATIONAL 723085 NGU NORFOLK  NAS 723086 PHF NEWPORT   NEWS 723087 FAF FORT  EUSTIS/FELKER 723088 63W MILFORD HAV EN CGS (B) (A) Figure 4-10.—View (A) is a section of a 1:4,000,000 scale DOD WPC (shown just smaller than actual size), and view (B), WMO international station identification numbers and U.S. national station identification letters in the Norfolk, Virginia vicinity. WMO block numbers are indicated on the plotting charts, usually in large, pastel blue digits. And the boundaries of each block are drawn as thin pastel blue lines. A  complete  numerical  listing  of  WMO block/station numbers is contained in the  Master Weather  Station  Catalog  available  via  the  Bulletin Board System (BBS) from FNMOD Tinker AFB, Oklahoma. The publication contains listings of country names  cross-referenced  to  block  number.  The information provided for each station includes latitude, longitude,  elevation,  information  on  the  coordinates and elevation of the upper-air observation site, and the type of data and observations available.  The codes used in the listings are explained in the first section of the publication. Other station circles may be drawn on the same chart, but identified with either a four-letter ICAO station identifier, such as EGUN, outside of the United States, or a three-letter (or letter/number) national station identifier, such as NGU or 63W within the United  States. ICAO Station Identifiers Within most countries, except the United States, airfields  and  their  weather  observation  sites  are identified with a four-letter identifier assigned by the International Civil Aviation Organization (ICAO). The first  letter  is  a  regional  identifier.  The  regional identifier is used to identify specific groups of countries in geographical areas of the world, such as M for the Caribbean and Mexico, K for the United States, or P for the Pacific. The second letter is specific to a particular country in the region, although a single large country may use several different letters as the second letter in the airfield identifier. For example, in Southeast Asia, Thailand uses ICAO four-letter identifiers beginning with the region identifier V, followed by the country identifier  T.  For  example,  Don  Muong  Airport, Bangkok,   Thailand   is   VTBD.   No   particular relationship exists between the ICAO identifier and the city name or airfield name. Within the Unites States, most airfields that report aviation weather use the three-letter national airfield identifiers, such as DAB for Daytona Beach Regional Airport, Daytona Beach, Florida, or BIS for Bismarck Municipal Airport, Bismarck, North Dakota, as the weather  station  identifier.  Most  of  these  identifiers, assigned  by  the  Federal  Aviation  Administration (FAA), are similar to the city or airfield name. Naval and Marine Corps air stations are nearly all identified by a three-letter identifier beginning with an N. Many automated weather reporting stations are identified by three-letter/number  combinations,  such  as  63W,  as  seen in figure 4-10. Several years ago, the FAA assigned the three-letter/number identifiers to heliports and airfields that were not manned by air-traffic controllers. Even though some of these stations do provide weather observations,  many  do  not.  (Currently,  the  FAA  assigns unmanned airfields a combination two-letter, two- number  identifier.) In the United States, ICAO identifiers were made by simply prefixing the three-letter national identifier with the ICAO region identifier K. Airfields equipped to  handle  international  air  traffic  use  the  ICAO identifier  as  both  an  airfield  identifier  and  as  a communications  identifier  for  weather  observations 4-11