What does 'O' stand for?

[sharpshooter41]

Dear All

What does 'O' in OMDB stand for?? Does it denote the region.....

Thanks in advance

[flowman]

It's the region, it doesn't stand for anything in particular, "Over there!" maybe.:)
Countries in that region with the indicator prefixed by O are:
Bahrain, Saudi Arabia, Iran, Jordan, Kuwait, Lebanon, UAE, Oman, Pakistan, Iraq, Syria, Qatar and Yemen.
flowman

[ATCO1962]

Hi sharp,

If you're at an ATC unit, just ask for the ICAO location indicator decoding book. It has an excellent, fold-out map that shows all the various regions and their associated identifying region letters. If I recall correctly, they don't possess any real logic to them; they are a hang-over from the past when the AFTN couldn't handle a lot of figures. I sometimes wonder why plain language hasn't replaced a lot of the data put into FPLs, NOTAMs and the like.

We're stuck with them for now. Cheers.

[bottom rung]

"O" my god its hot?

[sharpshooter41]

Thanks for the replies and 'bottom rung' That's a good one indeed. Wait till we really get into the summer season. :) Hot enough to fry eggs on the tarmac!!!!!

[Rule3]

ATCO1962

You are too modest, it stands for OMAN centre of the Region.:ok::D:ugh::=:*:confused:

[Aviator_IT]

From what I've figured out, some countries have the second letter as a designator. Examples:

LATI - Tirana, Albania
LGTS - Thessaloniki, Greece
LBSF - Sofia, Bulgaria
EDDL - Dusseldorf, Germany (Deutschland)
LIMC - Milano, Italy
EPWR - Wroclaw, Poland
LFPB - Le Bourget, France
ENGM - Oslo, Norway

And the list goes on...

Yet, there are many that have no resemblance at all...

LWSK - Skopje, Macedonia
LJLJ - Ljubljana, Slovenia
EKCH - Copenhagen, Denmark

It could be a coincidence, I am not sure...

Somebody with more knowledge could tell us.

[reportyourlevel]

The definitive reference is ICAO DOC 7910: Location Indicators, but you need a suscription to get it. Wikipedia, although sometimes questioned for its accuracy, gives us this map: http://upload.wikimedia.org/wikipedia/en/3/3b/ICAO-countries.png

[roljoe]

Hi,

my small contribution to this...

E stand for (Europe , mainly north europe)
L stand for latin contries like Italy, france, spain etc...

second letter for the contry..B for Belgium, E for Spain ( epagnol) etc..

for some contry 3th letter stand for region..ex lfPb P = Paris

Latest letter sometimes related to the city but no real rule..

[Green on, Go!]

Years ago, Australia had A. For example:

ASCB - Canberra
ASSY - Sydney

At an ICAO meeting it was decided that a different system was going to be used to determine the location idenifiers.

The Australian respresentative put up his hand and asked, 'Why?'

Therefore, Australia got Y.:ok:

In Oz the second letter generally relates to the FIR, although many places are a throwback to when there were more that the current 2 FIRs. For example:

YMML - Melbourne, in the Melbourne FIR
YPPH - Perth, formally in the Perth FIR but now in the ML FIR
Y

[ATCO1962]

Hi Rule 3,

You're right; modesty prevented me from mentioning that. As an aside, Oman does have an historical claim to large parts of the UAE. Remember, it was Oman and the Trucial States:eek:

Just waiting for the cross-border skirmishing to start:ok:

[Dr. Evil]

Hi roljoe

Correct me if I'm wrong but I believe L stands for the Levant countries

[Thylakoid]

Minor contribution: The "E" in Spain is for España

Some areas, such as South America: SBRF (eg.) South, Brazil, Recife

Places like Canada, for instance: CYKZ for Buttonville.
Actually, many, many places in Canada have codes that don't make any sense at all.

:)

[Lon More]

From the old AFTN designators; Denmark uses EK because ED was already allocated to West Germany. ( East germany had ET IIRC) EK fits nicely with Køpenhagen.

In the UK the third letter designated the circuit therefore GW for Luton and GD for bristol Lulsgate and for most (all?) civilian airfields in Scotland having P, Q for the military


Of course, this was all still in the future when I started.:)

[WestWind1950]

as has already been mentioned, "E" is for most of Europe. The second letter "D" for Germany from "Deutschland". Most large international airfields have a second "D", then the letter fitting it, if available.... like Frankfurt= EDDF, Hamburg=EDDH, etc. After the wall fell, all civilian fields kept the "ED__", the military ones were then given the "ET__" formerly used by the East German fields, as already mentioned.

Other fields are given indicators relating to the next big airport plus their own name, when possible. Egelsbach near Frankfurt has EDFE (FE=Frankfurt / Egelsbach), EDFM=Mannheim.

Since you can only have so many combinations with 4 letters, some indicators make no sense... though sometimes still do if you look at them closer. Aschaffenburg has EDFC. F=Frankfurt, C= VOR "Charlie", located nearby. Or a small field north of Frankfurt, EDGR=Giessen-Reiskirchen. Some may have historical meanings that are no longer clear.

But does it really matter? :rolleyes:

[Helen49]

The first letter of a Location Indicator identifies the ICAO Region.
H49

[Phantom99]

I seem to recall that in the UK the fields with a the same last two letters eg EGCC and EGHH were flight plan processing units before it became more centralised.

[vintage ATCO]

In the UK the third letter designated the circuit therefore GW for Luton and GD for bristol Lulsgate and for most (all?) civilian airfields in Scotland having P, Q for the military

Showing your age now, Lon . . . . :)

Luton used to be EGLN when connected to Heathrow Comms Centre, then became EGGW when connected to the (then) 'new' Croydon Comms Centre (went there once, Jeeez!) Now everyone is (sort of) connected to Heathrow again. Happy days. :ok:

[Lon More]

That was a bit before our time i think Steve.
It lives on , I see, EGLN London/Heathrow (Southern Area Maintenance Unit).

BTW Re Croydon. Wasn't one of Luton Flying Club's Moths the last aircraft to land there, after the airfield had officially closed? An engine problem or WX?

Happy days; Phil Jeffrey and me in a C150, but we didn't have the suffix 'heavy' then:)

[say what]

Hey Green on Go .....flip bro that Aussie Y thing was funny ....true or not ....it's funny .....I laughed no end .... :D

[Short Approach?]

EKYT (Aalborg) got that designator because it's "secret code" was yellow target during WW II

[SU-GCM]

I would like to add a note
OEJN is Jeddah Airport
OEJD is Jeddah Center

HECA is Cairo Intl
HECC is Cairo Center

I have heared that The E in oEjd and the E in hEcc
is dueto Egypt was responsible for all ATC Operations with in Saudi Airspace and the ICAO haven't changed the letter

is that correct ?????

[A I]

Hi Lon,

And there was a certain (now retired) EGLL ATCO who dropped into Croydon very early one morning in about 1981 just to get it in his logbook. I could give the registration of the aircraft but then I'd have to shoot myself. (It was French)

A I :)

[RAC/OPS]

I thought O stood for Oil

[Aviator_IT]

It's been a while since we've discussed this topic, but I accidently found a good explanation we were looking for.

Airport ABCs: An Explanation of Airport Identifier Codes

This article was published in the journal of the Air Line Pilots Association, Air Line Pilot, in December of 1994. I wrote it, but ALPA holds the copyright and reserves all rights other then you reading it directly from this Internet page. This online version is kept updated and revised.



From ABE (Allentown/Bethlehem/Easton, Pennsylvania) to ZRH (Zurich, Switzerland), airports around the world are universally known by a unique three-letter code: the "International Air Transport Association (IATA) Location Identifier" in aviation-speak. It's obviously much easier for pilots, controllers, travel agents, frequent flyers, computers and baggage handlers to say and write ORD than the O'Hare International Airport in Chicago, Illinois—but how did this practice start, and why are some airport codes easy to understand (ABE and ZRH) while others seem to make absolutely no sense (ORD)?

When the Wright brothers first took to the air in 1903, there was no need for coding airports since an airport was literally any convenient field with a strong wind. However, the National Weather Service did tabulate data from cities around the country using a two-letter identification system. Early airlines simply copied this system, but as airline service exploded in the 1930's, towns without weather station codes needed identification. Some bureaucrat had a brainstorm and the three-letter system was born, giving a seemingly endless 17,576 different combinations. To ease the transition, existing airports placed an X after the weather station code. The Los Angeles tag became LAX, Portland became PDX, Phoenix became PHX and so on. Incidentally at the historic sand dune in Kitty Hawk where the first flight occurred the U.S. National Parks Service maintains a tiny airstrip called FFA—First Flight Airport.

Many station codes are simply the first three letters of the city name: ATL is Atlanta, BOS is Boston, MIA is Miami, SIN is Singapore, and SYD is Sydney, Australia. The first letter(s) of multiple cities served forms other codes: DFW for Dallas Fort Worth, MSP for Minneapolis/St. Paul, and GSP for Greenville/Spartanburg, South Carolina. Sometimes the city name lends itself to one letter for each word, such as Salt Lake City (SLC), Port of Spain in Trinidad & Tobago (POS), or even Port au Prince, Haiti (PAP).

Most of the "hard to decipher" identifiers become obvious if one knows the name of the airport rather than the city served. A Louisiana example is ESF, for Esler Field in Alexandra. Orly airport (ORY) and Charles De Gaulle airport (CDG) serve Paris, France, while Tokyo, Japan has the Narita airport (NRT). When you know what the code represents, some curious acronyms become obvious: MSY is the former Moisant Stock Yards in New Orleans, CMH is Columbus Municipal Hangar, BWI is Baltimore Washington International, LGW is London Gatwick, and LHR is London Heathrow!

This system of identifying airports caught on quickly and soon expanded to include all radio navigation aids used by pilots. The VOR on the field at ORD sends out the Morse code for ORD. Recently some VORs not located at the airport of the same name changed identifiers to prevent possible confusion. The clearance "cross 10 miles south of Chattanooga" was confusing when the airport and VOR were five miles apart. FAA surprisingly didn't try to change the name of the city but changed the VOR, resulting in the Chattanooga Airport (CHA) and the Choo Choo VOR (GCO)!

All localizer identifiers are prefaced with an "I." Compass locators are assigned a two-letter identifier, normally using the localizer as a base. For example, at ABC the localizer might be IABC, the locator outer marker, AB, and the locator inner marker, BC. (Note, outside the US radio navigation aid naming may be much less formal.)

Some special interest groups successfully lobbied the government to obtain their own special letters. The Navy saved all the new 'N' codes. Naval aviators learn to fly at NPA in Pensacola, Florida and then dream of going to "Top Gun" in Miramar, California (NKX). The Federal Communications Committee set aside the 'W' and 'K' codes for radio stations east and west of the Mississippi respectively. 'Q' was designated for international telecommunications. 'Z' was reserved for special uses. The Canadians made off with all the remaining 'Y codes which helps explain YUL for Montreal, YYC for Calgary, etc. (The start of the the song YYZ by the band Rush is the Morse code for the letters Y Y Z. Rush is from Toronto.) One of the special uses for 'Z' is identifying locations in cyberspace. What am I talking about? Well, an example is ZCX the computer address of the FAA's air traffic control headquarters central flow control facility. ZCX is not an airport but a command center just outside Washington D.C., that controls the airline traffic into major terminals.

The lack of these letters puts a crimp in the logic of some codes: if the city starts with a 'N,' 'W,' or 'K,' it's time to get creative! Norfolk, Virginia, ignored the 'N' to get ORF; Newark, New Jersey, is EWR, Newport News, Virginia, chose to use the name of the airport to get PHF -Patrick Henry Field. Both Wilmington, North Carolina and Key West, Florida followed Norfolk's lead to obtain ILM and EYW. West Palm Beach in Florida did some rearranging to get PBI -Palm Beach International; Kansas City, Missouri became MKC and more recently the 'new' Kansas City airport chose MCI. (The code for Kansas City International Airport, MCI, was assigned during the early design phase of the airport when the name was going to be Mid-Continent International. Shortly before it opened, Kansas City officials decided to change the name so people would know what city it was in. It was too late to change the code.)

The continued growth of aviation world-wide meant that three letter combinations were insufficient to identify every airport. Eventually the system expanded, allowing numbers and four digit combinations; however, an airport served by scheduled route air-carrier or military airlift aircraft always has a code comprising of only three letters. Raleigh, North Carolina, not only has RDU (Raleigh/Durham International), but also the much smaller 5W5 (South Raleigh Airport), W17 (Raleigh East Airport), 2NC3 (Sky-5 helipad), and ONC4 (Wake Medical Center Heliport). The two-letter, two-number identifiers use the two-letter Post Office or supplemental abbreviation of the State for the two letters: 2ND9 is in North Dakota, 85FL is in Florida, etc. Hilton Head Island, South Carolina, known as 49J when it was a general aviation airport, now has airline service and therefore a new airport identifier—HHH.

Lacking both 'W' and 'N' Washington National has a code of DCA for District of Columbia Airport. The newer Dulles airport just outside D.C. was DIA (from Dulles International Airport); however, the DIA and DCA were easy to confuse, especially when hastily written in chalk on a baggage cart, scribbled on a tag or a handwritten air traffic control strip, so we are stuck with the backwards IAD. Now one of the rules of the game is "the first and second letters or second and third letters of an identifier may not be duplicated with less than 200 nautical miles separation."

Houston has HOU for the William B. Hobby airport. The 200 mile rule lead to the airport label of IAH, for the new Intercontinental Airport Houston. Louisville, Kentucky, already had an airport with the logical code of LOU; therefore, the letters for the new airport had to be something radically different: SDF stands for Standiford Field.

The airport ciphers sometimes don't originate with the city or airfield name but with the county in which it resides. Longview/Kilgore in Texas is GGG, from Gregg county airport. The 'W' in Detroit's DTW comes from Wayne county; the 'P' in Greenville's PGV comes from its location in Pitt County, North Carolina. However the John Wayne Airport serving Orange County takes its call letters from the less recognized Santa Ana (SNA).

A little more geography cracks the code for CVG, MDT and GTR. Cincinnati, Ohio, has its airport located in northern Kentucky (look at a map if you don't believe me!); therefore, Cincinnati's ID actually comes from the town of Covington - CVG. Harrisburg International is physically located in Middletown, Pennsylvania (MDT). Any Mississippi State Bulldogs' fan can tell you that Columbus, Starkville, and West Point form the Golden Triangle of Mississippi, with airline service at the Golden Triangle Regional Airport (GTR).

History, rather than geography, solves the puzzle of BNA, TYS, GEG, OGG and MCO. The main airport in Nashville, Tennessee, was named in honor of Col. Harry Berry who helped build it: BNA. Knoxville, also in Tennessee, doesn't have a single letter in common with its tag of TYS; however, a historian would know that the Tyson family donated the land in honor of their son killed in World War I. The current Orlando International Airport stands on the land that used to be McCoy Air Force Base (MCO). Spokane International Airport is coded as GEG in honor of Major Harold C. Geiger, a pioneer in Army aviation and ballooning. Geiger field was renamed in 1960 but the code was not changed. Kahului Airport, Maui, was designated as OGG in honor of aviation legend, and Lihue native, Capt. Bertram J. Hogg (pronounced Hoag).

One of the world's largest airports, JFK, is also one of the very few that changed call letters. A change is rare because an identifier becomes so well known to airline staff that changes are not normally permitted. Interestingly the John F. Kennedy airport's former code also came from the name of the field — IDL for Idlewild airport. If you knew that Fort Myers used to be called SouthWest Florida Regional, the RSW moniker starts to make sense. A code used by American Airlines but never seen by the traveling public is GSW. Pilots spend months at GSW, but no planes land or take-off there. The mystery is solved when you discover that Americans' Flight Academy, with its many simulators and classrooms, is in Ft. Worth on the former site of the Greater SouthWest Airport. A airport that has worked hard to change its given code is Sioux City's Sioux Gateway Airport—SUX. Mayor Craig Berenstein described the SUX code as an "embarrassment". City leaders petitioned the FAA to change the code in 1998 and again in 2002. At one point the FAA offered the city five alternatives—GWU, GYO, GYT, SGV and GAY—but airport trustees didn't like any of them enough to change. In 2007 the airport made the best of their sucky cipher and started promoting the airport with the slogan "FLY SUX."

Years ago, entire metropolitan areas were given a code to include many airports; NYC covered New York City and LON signified London. Unfortunately there are no new metropolitan area codes due to the scarcity of letters. These codes provide the ability to quickly look up in a computerized reservation system all the flights to a certain city without using separate codes for each airport. Entering WAS as a designation will give me the next few flights to BWI, IAD and DCA—the Washington, D.C. area. In fact, three letter codes are so scarce that after a year they can be recycled: when Idlewild Airport became JFK, the old IDL tag was retired then reused for Indianola, Mississippi.

Airlines use the three-letter codes internationally in their own network, Sita, for messages such as passenger loads and departure times. World ATC and weather agencies use a separate teleprinter network, the Aeronautical Fixed Telecommunications Network (AFTN), which uses a four-letter "location indicator." Going from large area to actual airport, the first letter relates to the part of the world and the second letter the country. The third letter is a group of airports within that country. Most countries who use this particular convention use a letter to denote the FIR in which the airport is located. So F is Frankfurt FIR in Germany, M is Munich; P is Paris FIR, M is Marseilles. Other ways to use the third letter include identifying a group of airports with a common factor. For example, A was used in Germany for all Canadian and American air force bases. The last letter positively identifies a specific airport.

Thus Aberdeen, Scotland, has the International Civil Aviation Organization (ICAO) location indicator of EGPD—E for Northern Europe, G for United Kingdom, P for Scottish region, and D for Dyce field. Want to figure out LFPG? It's L for southern Europe, F for France, P for Paris FIR, and G for Charles de Gaulle airport. Easy! Another example to decode is EDMM. E for northern Europe, D for Deutchland (Germany), M for Munchen (Munich) FIR, and M again for the Munich airport. Some are more easy to remember. The Dominican Republic codes all start with M (Central America) and D (Dominican) and then, well, see if you spot the code for international airports in Santo Domingo (MDSD), La Romana (MDLR), Puerto Plata (MDPP), Punta Cana (MDPC) and Santiago (MDST).

So if London Heathrow has two codes — and it does, LHR and EGLL — how come I've heard Chicago O'Hare only called ORD? The answer is unique to the United States. In the 48 contiguous States the ICAO code is formed simply by adding a "K" to the FAA code. This explains why international flight plans refer to KORD, KMIA, KJFK, etc. A meeting of two rules is Key West, the FAA code is EYW (lose the 'K') and the IATA code is KEYW (add a 'K') which works great for KEY West.

Other airports within FAA jurisdiction have ICAO codes usually formed by taking two letters from the FAA name and prefixing them with PA for Alaska, PH for Hawaii, or PG for Guam. PT appears to be Pacific Trust Territories (Pohnpei, Yap, Chuuk, etc.), and there are various random other P codes like PWAK for Wake Island.

Instrument pilots are familiar with another type of identifier, not for an airport or navigation aid but simply for a point in space. Every airway intersection is a five letter, supposedly pronounceable, combination, from AADCO to ZZARP. Just like airports, some fixes are named after towns: close to Raleigh, N.C., are DUHAM (over Durham) and CHAPL (over Chapel Hill) intersections. Some are named after people or events, and others are named just for fun: BORED, BUILT, BUTCH. The excellent book Chasing The Glory, by Michael Parfit, introduces us to the woman who names intersections, Macho Irene. She dreams of some pompous B-747 captain saying, "Roger, will report MUMMI."

From LA to DUHAM, identifiers have grown in complexity and are now used as computer codes in vast reservations systems and flight management computers. The latest trend in bag-tagging technology is laser printed bar codes for automated luggage systems. Will # ## # ## ever completely replace DFW? The answer may be found at DIA, the new Denver International Airport which used identifier DVX when the runways opened for testing, but inherited the familiar DEN code when Denver's Stapleton airport closed down.

Oh, still wondering about the world's busiest airport, O'Hare International, and its ORD code? Well once upon a time, before the editor and publisher of the Chicago Tribune, Colonel Robert McCormick suggested a name change as tribute to pilot Lt. Cmdr. Edward "Butch" O'Hare, United States Navy, there was an airstrip well to the northwest of Chicago with a quaint, peaceful name—Orchard Field.

Airport Codes: The ABC's** A History and Explanation (http://www.skygod.com/asstd/abc.html)

[vintage ATCO]

Another example to decode is EDMM. E for northern Europe, D for Deutchland (Germany), M for Munchen (Munich) FIR, and M again for the Munich airport.Forgive me as I haven't read the full article (but will later, I find the subject fascinating even though retired, sad, eh? :) ) but EDMM is the ACC at Munich, the airport is EDDM. In the days when I was addressing FPLs the ACC was also EDDM but was changed, as other German ACCs were, to differentiate them from the airports.

I have just noticed in the latest Doc7910 (ed 127 Mar 08) that it now contains the IATA three letter codes. How long has that been the case? Would have helped enormously, the airlines always spoke in IATA codes which I never got to grips with. Give me ICAO any time! :) :) :)

[grizzled]

Somebody ought to take a second look at the decision regarding the identifier for the new Jebeli Airport (soon to be the world's largest: six parallel runways, etc). It's "JXB" and it lies just a few short miles from DXB (Dubai). If that doesn't get changed soon, I'll bet a pocketfull of Dhirhams that lost luggage, lost and incorrectly loaded PAX, and even mis-vectored A/C will be routine occurrences.

On the serious side, if not amended, it's bound to be an ingredient in a nasty recipe where the holes in the cheese line up one day . . .

Grizz

[Tower Ranger]

The Scottish ones always made sense, Daberdeen, Hedinburgh, Flasgow, Terth, Krestwick, Nundee, Enverness
See Perfect sense!!

[chiglet]

I think that the Canadian airfields just added a "C" to the relevant "Radio Range" beacon/W/T station that was on the said airfield.
watp,iktch

[Farrell]

The "O" doesn't stand for anything. It is just a regional classification letter.

A - Western South Pacific

AG Solomon Islands
AN Nauru
AY Papua New Guinea

B - Iceland/Greenland

BG Greenland
BI Iceland

C - Canada

C Canada

D - West Africa

DA Algeria
DB Benin
DF Burkina Faso
DG Ghana
DI Côte d'Ivoire
DN Nigeria
DR Niger
DT Tunisia
DX Togolese Republic

E - Northern Europe

EB Belgium
ED Germany (civil)
EE Estonia
EF Finland
EG United Kingdom
EH Netherlands
EI Ireland
EK Denmark
EL Luxembourg
EN Norway
EP Poland
ES Sweden
ET Germany (military)
EV Latvia
EY Lithuania

F - Southern Africa

FA South Africa
FB Botswana
FC Republic of the Congo
FD Swaziland
FE Central African Republic
FG Equatorial Guinea
FH Ascension Island
FI Mauritius
FJ British Indian Ocean Territory
FK Cameroon
FL Zambia
FM Comoros, Madagascar, Mayotte, Réunion
FN Angola
FO Gabon
FP São Tomé and Príncipe
FQ Mozambique
FS Seychelles
FT Chad
FV Zimbabwe
FW Malawi
FX Lesotho
FY Namibia
FZ Democratic Republic of the Congo

G - Northwestern Africa

GA Mali
GB The Gambia
GC Canary Islands (Spain)
GE Ceuta and Melilla (Spain)
GF Sierra Leone
GG Guinea-Bissau
GL Liberia
GM Morocco
GO Senegal
GQ Mauritania
GS Western Sahara
GU Guinea
GV Cape Verde

H - Northeastern Africa

HA Ethiopia
HB Burundi
HC Somalia
HD Djibouti (also HF)
HE Egypt
HF Djibouti (also HD)
HH Eritrea
HK Kenya
HL Libya
HR Rwanda
HS Sudan
HT Tanzania
HU Uganda

K - USA

K Contiguous United States of America

L - Southern Europe,Israel and Turkey

LA Albania
LB Bulgaria
LC Cyprus
LD Croatia
LE Spain
LF France, including Saint-Pierre and Miquelon
LG Greece
LH Hungary
LI Italy
LJ Slovenia
LK Czech Republic
LL Israel
LM Malta
LN Monaco
LO Austria
LP Portugal, including the Azores
LQ Bosnia and Herzegovina
LR Romania
LS Switzerland
LT Turkey
LU Moldova
LV Gaza Strip
LW Macedonia
LX Gibraltar
LY Serbia and Montenegro
LZ Slovakia

M - Central America and Mexico

MB Turks and Caicos Islands
MD Dominican Republic
MG Guatemala
MH Honduras
MK Jamaica
MM Mexico
MN Nicaragua
MP Panama
MR Costa Rica
MS El Salvador
MT Haiti
MU Cuba
MW Cayman Islands
MY Bahamas
MZ Belize

N - South Pacific

NC Cook Islands
NF Fiji, Tonga
NG Kiribati (Gilbert Islands), Tuvalu
NI Niue
NL Wallis and Futuna
NS Samoa, American Samoa
NT French Polynesia
NV Vanuatu
NW New Caledonia
NZ New Zealand, Antarctica

O - Southwest Asia (excluding Israel and Turkey), Afghanistan and Pakistan

OA Afghanistan
OB Bahrain
OE Saudi Arabia
OI Iran
OJ Jordan and the West Bank
OK Kuwait
OL Lebanon
OM United Arab Emirates
OO Oman
OP Pakistan
OR Iraq
OS Syria
OT Qatar
OY Yemen

P - Eastern North Pacific

PA Alaska only
PB Baker Island
PC Kiribati (Canton Airfield, Phoenix Islands)
PF Fort Yukon, Alaska
PG Guam, Northern Marianas
PH Hawaiʻi only
PJ Johnston Atoll
PK Marshall Islands
PL Kiribati (Line Islands)
PM Midway Island
PO Oliktok Point, Alaska
PP Point Lay, Alaska
PT Federated States of Micronesia, Palau
PW Wake Island

R - Western North Pacific

RC Republic of China (Taiwan)
RJ Japan (most of country)
RK South Korea
RO Japan (Okinawa Prefecture and Yoron)
RP Philippines

S - South America

SA Argentina
SB Brazil (also SD, SN, SS and SW)
SC Chile
SD Brazil (also SB, SN, SS and SW)
SE Ecuador
SF Falkland Islands
SG Paraguay
SK Colombia
SL Bolivia
SM Suriname
SN Brazil (also SB, SD, SS and SW)
SO French Guiana
SP Peru
SS Brazil (also SB, SD, SN and SW)
SU Uruguay
SV Venezuela
SW Brazil (also SB, SD, SN and SS)
SY Guyana

T - Caribbean

TA Antigua and Barbuda
TB Barbados
TD Dominica
TF Guadeloupe
TG Grenada
TI U.S. Virgin Islands
TJ Puerto Rico
TK Saint Kitts and Nevis
TL Saint Lucia
TN Netherlands Antilles, Aruba
TQ Anguilla
TR Montserrat
TT Trinidad and Tobago
TU British Virgin Islands
TV Saint Vincent and the Grenadines
TX Bermuda

U - Russia and former Soviet States

U Russia (except UA, UB, UD, UG, UK, UM and UT)
UA Kazakhstan, Kyrgyzstan
UB Azerbaijan
UD Armenia
UG Georgia
UK Ukraine
UM Belarus
UT Tajikistan, Turkmenistan, Uzbekistan

V - South Asia (except Afghanistan and Pakistan) and mainland Southeast Asia

VA India (West Zone, Mumbai Center)
VC Sri Lanka
VD Cambodia
VE India (East Zone, Kolkata Center)
VG Bangladesh
VH Hong Kong, China
VI India (North Zone, Delhi Center)
VL Laos
VM Macau, China
VN Nepal
VO India (South Zone, Chennai Center)
VQ Bhutan
VR Maldives
VT Thailand
VV Vietnam
VY Myanmar

W - Maritime Southeast Asia (except the Philippines)

WA Indonesia (also WI, WQ and WR)
WB Malaysia (also WM), Brunei
WI Indonesia (also WA, WQ and WR)
WM Malaysia (also WB)
WP Timor-Leste
WQ Indonesia (also WA, WI and WR)
WR Indonesia (also WA, WI and WQ)
WS Singapore

Y - Australia

Y Australia

Z - China, Mongolia and North Korea

Z People's Republic of China (except ZK and ZM)
ZK North Korea
ZM Mongolia

[LapSap]

I know its been answered on here somewhere before, but when I see EGGW I can't help think the obvious answer is Gatwick when in fact its Luton. Anyone care to explain how that came about?

[windowjob]

What about the one that was invented for Hayes heliport, north of Heathrow?
There were regular test/demo flights in/out and we got fed up with writing Hayes all the time so "invented" EGHZ. As you only used the last 2 letters if it started EG when writing on strips it was quicker. Why EGHZ? Well when the met came through it used to say Vis 2000m HZ (Haze - geddit) You won't find it anywhere official mind.

[vintage ATCO]

I know its been answered on here somewhere before, but when I see EGGW I can't help think the obvious answer is Gatwick when in fact its Luton. Anyone care to explain how that came about?Yep! :)

There was a time when some major airfields acted as comms centres for others to connect to, they were the ones with the double letters at the end - EGLL, EGSS etc. Luton was EGLN and connected to the AFTN via Heathrow EGLL. When a 'new' comms centre was opened at Croydon that became EGGG and Luton's link was transferred to it and became EGGW. I guess W was just a spare letter although I think this explanation falls down a bit when you consider that Shawick Oceanic is EGGX! At around the same time Elstree's AFTN link was moved from Heathrow to West Drayton so changed from EGLE to EGTR.

Today it doesn't work like that but, by and large, they do seem to be allocated geographically.