<s>
Common	B-Algorithm
traffic	I-Algorithm
advisory	I-Algorithm
frequency	I-Algorithm
(	O
CTAF	B-Algorithm
)	O
is	O
the	O
name	O
given	O
to	O
the	O
VHF	B-Algorithm
radio	O
frequency	O
used	O
for	O
air-to-air	O
communication	O
at	O
United	O
States	O
,	O
Canadian	O
and	O
Australian	O
non-towered	O
airports	O
.	O
</s>
<s>
In	O
Canada	O
,	O
the	O
lighting	O
system	O
is	O
accessed	O
through	O
an	O
aircraft	O
radio	O
control	O
of	O
aerodrome	O
lighting	O
(	O
ARCAL	O
)	O
frequency	O
,	O
which	O
is	O
often	O
shared	O
with	O
the	O
CTAF	B-Algorithm
.	O
</s>
<s>
Two	O
common	O
CTAF	B-Algorithm
allocations	O
are	O
UNICOM	B-Algorithm
and	O
MULTICOM	B-Algorithm
.	O
</s>
<s>
UNICOM	B-Algorithm
is	O
a	O
licensed	O
non-government	O
base	O
station	O
that	O
provides	O
air-to-ground	O
and	O
ground-to-air	O
communication	O
,	O
and	O
may	O
also	O
serve	O
as	O
a	O
CTAF	B-Algorithm
when	O
in	O
operation	O
.	O
</s>
<s>
MULTICOM	B-Algorithm
is	O
a	O
frequency	O
allocation	O
without	O
a	O
physical	O
base	O
station	O
that	O
is	O
reserved	O
as	O
a	O
CTAF	B-Algorithm
for	O
airports	O
without	O
other	O
facilities	O
.	O
</s>
<s>
In	O
Australia	O
,	O
there	O
are	O
many	O
landing	O
strips	O
in	O
remote	O
locations	O
that	O
have	O
CTAF	B-Algorithm
operations	O
24	O
hours	O
a	O
day	O
,	O
seven	O
days	O
a	O
week	O
.	O
</s>
<s>
There	O
are	O
also	O
CTAF(R )	O
landing	O
strips	O
which	O
require	O
the	O
aircraft	O
intending	O
to	O
enter	O
the	O
area	O
of	O
operation	O
to	O
be	O
fitted	O
with	O
a	O
radio	O
.	O
</s>
<s>
The	O
most	O
common	O
CTAF	B-Algorithm
frequency	O
is	O
126.7MHz	O
at	O
non-towered	O
aerodromes	O
,	O
except	O
for	O
when	O
two	O
CTAF	B-Algorithm
airports	O
are	O
near	O
each	O
other	O
.	O
</s>
<s>
Aerodromes	O
using	O
CTAF	B-Algorithm
outside	O
tower	O
hours	O
typically	O
nominate	O
a	O
frequency	O
that	O
is	O
used	O
during	O
tower	O
hours	O
.	O
</s>
<s>
UNICOM	B-Algorithm
and	O
a	O
CTAF	B-Algorithm
may	O
be	O
mutually	O
exclusive	O
,	O
but	O
this	O
is	O
not	O
always	O
the	O
case	O
.	O
</s>
<s>
In	O
the	O
United	O
States	O
,	O
many	O
non-towered	O
airports	O
use	O
the	O
same	O
frequency	O
for	O
both	O
UNICOM	B-Algorithm
and	O
CTAF	B-Algorithm
purposes	O
.	O
</s>
<s>
Pilots	O
are	O
advised	O
to	O
check	O
their	O
sectional	O
charts	O
and/or	O
Chart	O
Supplement	O
(	O
formerly	O
Airport/Facilities	O
Directory	O
)	O
to	O
determine	O
the	O
appropriate	O
frequency	O
for	O
CTAF	B-Algorithm
prior	O
to	O
operating	O
at	O
any	O
given	O
airport	O
.	O
</s>
