<s>
The	O
ICAO	B-General_Concept
airport	I-General_Concept
code	I-General_Concept
or	O
location	O
indicator	O
is	O
a	O
four-letter	O
code	O
designating	O
aerodromes	O
around	O
the	O
world	O
.	O
</s>
<s>
These	O
codes	O
,	O
as	O
defined	O
by	O
the	O
International	B-General_Concept
Civil	I-General_Concept
Aviation	I-General_Concept
Organization	I-General_Concept
and	O
published	O
in	O
ICAO	B-General_Concept
Document	O
7910	O
:	O
Location	O
Indicators	O
,	O
are	O
used	O
by	O
air	B-Application
traffic	I-Application
control	I-Application
and	O
airline	O
operations	O
such	O
as	O
flight	O
planning	O
.	O
</s>
<s>
ICAO	B-General_Concept
codes	O
are	O
also	O
used	O
to	O
identify	O
other	O
aviation	O
facilities	O
such	O
as	O
weather	O
stations	O
,	O
international	O
flight	O
service	O
stations	O
or	O
area	O
control	O
centers	O
,	O
whether	O
or	O
not	O
they	O
are	O
located	O
at	O
airports	O
.	O
</s>
<s>
Flight	O
information	O
regions	O
are	O
also	O
identified	O
by	O
a	O
unique	O
ICAO-code	O
.	O
</s>
<s>
The	O
International	B-General_Concept
Civil	I-General_Concept
Aviation	I-General_Concept
Organization	I-General_Concept
was	O
formed	O
in	O
1947	O
under	O
the	O
auspices	O
of	O
the	O
United	O
Nations	O
,	O
and	O
it	O
established	O
flight	O
information	O
regions	O
(	O
FIRs	O
)	O
for	O
controlling	O
air	B-Application
traffic	I-Application
and	O
making	O
airport	O
identification	O
simple	O
and	O
clear	O
.	O
</s>
<s>
ICAO	B-General_Concept
codes	O
are	O
separate	O
and	O
different	O
from	O
IATA	O
codes	O
,	O
which	O
are	O
generally	O
used	O
for	O
airline	O
timetables	O
,	O
reservations	O
,	O
and	O
baggage	O
tags	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
IATA	O
code	O
for	O
London	O
's	O
Heathrow	O
Airport	O
is	O
LHR	O
and	O
its	O
ICAO	B-General_Concept
code	O
is	O
EGLL	O
.	O
</s>
<s>
ICAO	B-General_Concept
codes	O
are	O
commonly	O
seen	O
by	O
passengers	O
and	O
the	O
general	O
public	O
on	O
flight-tracking	O
services	O
such	O
as	O
FlightAware	B-Application
.	O
</s>
<s>
In	O
general	O
IATA	O
codes	O
are	O
usually	O
derived	O
from	O
the	O
name	O
of	O
the	O
airport	O
or	O
the	O
city	O
it	O
serves	O
,	O
while	O
ICAO	B-General_Concept
codes	O
are	O
distributed	O
by	O
region	O
and	O
country	O
.	O
</s>
<s>
Far	O
more	O
aerodromes	O
(	O
in	O
the	O
broad	O
sense	O
)	O
have	O
ICAO	B-General_Concept
codes	O
than	O
IATA	O
codes	O
,	O
which	O
are	O
sometimes	O
assigned	O
to	O
railway	O
stations	O
as	O
well	O
.	O
</s>
<s>
Selection	O
of	O
ICAO	B-General_Concept
codes	O
is	O
partly	O
delegated	O
to	O
authorities	O
in	O
each	O
country	O
,	O
while	O
IATA	O
codes	O
which	O
have	O
no	O
geographic	O
structure	O
must	O
be	O
decided	O
centrally	O
by	O
IATA	O
.	O
</s>
<s>
Typically	O
,	O
the	O
first	O
one	O
or	O
two	O
letters	O
of	O
the	O
ICAO	B-General_Concept
code	O
indicate	O
the	O
country	O
and	O
the	O
remaining	O
letters	O
identify	O
the	O
airport	O
,	O
as	O
indicated	O
by	O
the	O
adjoining	O
figures	O
.	O
</s>
<s>
ICAO	B-General_Concept
codes	O
provide	O
geographical	O
context	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
one	O
knows	O
that	O
the	O
ICAO	B-General_Concept
code	O
for	O
Heathrow	O
is	O
EGLL	O
,	O
then	O
one	O
can	O
deduce	O
that	O
the	O
airport	O
EGGP	O
is	O
somewhere	O
in	O
the	O
UK	O
(	O
it	O
is	O
Liverpool	O
John	O
Lennon	O
Airport	O
)	O
.	O
</s>
<s>
There	O
are	O
a	O
few	O
exceptions	O
to	O
the	O
regional	O
structure	O
of	O
the	O
ICAO	B-General_Concept
code	O
made	O
for	O
political	O
or	O
administrative	O
reasons	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
RAF	O
Mount	O
Pleasant	O
air	O
base	O
in	O
the	O
Falkland	O
Islands	O
is	O
assigned	O
the	O
ICAO	B-General_Concept
code	O
EGYP	O
as	O
though	O
it	O
were	O
in	O
the	O
United	O
Kingdom	O
,	O
but	O
nearby	O
civilian	O
Port	O
Stanley	O
Airport	O
is	O
assigned	O
SFAL	O
,	O
consistent	O
with	O
South	O
America	O
.	O
</s>
<s>
In	O
the	O
contiguous	O
United	O
States	O
and	O
Canada	O
,	O
many	O
airports	O
have	O
ICAO	B-General_Concept
codes	O
that	O
are	O
simply	O
copies	O
of	O
their	O
three-letter	O
IATA	O
codes	O
,	O
with	O
the	O
geographical	O
prefix	O
added	O
on	O
(	O
e.g.	O
,	O
YEG	O
and	O
CYEG	O
both	O
refer	O
to	O
Edmonton	O
International	O
Airport	O
,	O
while	O
IAD	O
and	O
KIAD	O
both	O
refer	O
to	O
Washington	O
Dulles	O
International	O
Airport	O
)	O
.	O
</s>
<s>
As	O
an	O
example	O
,	O
Kahului	O
International	O
Airport	O
on	O
Maui	O
has	O
an	O
IATA	O
code	O
of	O
OGG	O
and	O
an	O
ICAO	B-General_Concept
code	O
of	O
PHOG	O
.	O
</s>
<s>
ICAO	B-General_Concept
airport	I-General_Concept
codes	I-General_Concept
do	O
not	O
begin	O
with	O
I	O
or	O
J	O
or	O
X	O
or	O
Q	O
,	O
though	O
the	O
Jezero	O
Crater	O
on	O
Mars	B-Application
is	O
assigned	O
the	O
special	O
ICAO	B-General_Concept
code	O
JZRO	O
.	O
</s>
<s>
In	O
Russia	O
and	O
the	O
CIS	O
,	O
Latin	O
letter	O
X	O
(	O
or	O
its	O
Morse/Baudot	O
Cyrillic	O
equivalent	O
Ь	O
)	O
is	O
used	O
to	O
designate	O
government	O
,	O
military	O
and	O
experimental	O
aviation	O
airfields	O
in	O
internal	O
airfield	O
codes	O
similar	O
in	O
structure	O
and	O
purpose	O
to	O
ICAO	B-General_Concept
codes	O
but	O
not	O
used	O
internationally	O
.	O
</s>
<s>
ZZZZ	O
is	O
a	O
pseudo-code	O
,	O
used	O
in	O
flight	O
plans	O
for	O
aerodromes	O
with	O
no	O
ICAO	B-General_Concept
code	O
assigned	O
.	O
</s>
<s>
In	O
small	O
countries	O
like	O
Belgium	O
or	O
the	O
Netherlands	O
,	O
almost	O
all	O
aerodromes	O
have	O
an	O
ICAO	B-General_Concept
code	O
.	O
</s>
<s>
Some	O
countries	O
have	O
addressed	O
this	O
issue	O
by	O
introducing	O
a	O
scheme	O
of	O
sub-ICAO	O
aerodrome	O
codes	O
;	O
France	O
,	O
for	O
example	O
,	O
assigns	O
pseudo-ICAO	O
codes	O
in	O
the	O
style	O
LFddnn	O
,	O
where	O
dd	O
indicates	O
the	O
department	O
while	O
nn	O
is	O
a	O
sequential	O
counter	O
.	O
</s>
<s>
In	O
Antarctica	O
many	O
aerodromes	O
have	O
pseudo	O
ICAO-codes	O
with	O
AT	O
and	O
two	O
digits	O
,	O
while	O
others	O
have	O
proper	O
codes	O
from	O
base	O
owner	O
countries	O
such	O
as	O
NZ	O
for	O
New	O
Zealand	O
.	O
</s>
