CL C class C airspace (VFR frequency)
CLR clearance delivery
CTA control area (VFR frequency used outside the U.S.)
CTAF common traffic advisory frequency
CTR center (when center is used for approach/departure
control)
DEP departure
DIR director (approach control/radar)
GCO ground communications outlet
GRND ground control
MCOM multicom
MF mandatory frequency
PCL pilot-controlled lighting
PTAX pre-taxi clearance
RAMP ramp/taxi control
RDO radio
RDR radar-only frequency
TMA terminal area (VFR frequency used outside the U.S.)
TWR control tower
UNIC unicom
The Navigation abbreviations are:
ILS Instrument landing system approach
LOC Localizer approach
LBC Localizer back course
LDA Localizer type directional aid approach
SDF Simplified directional facility approach
Part-time operation, such as for a control tower, is indicated with an aster-
isk (*) to the right of an airport frequency.
The frequencies associated with class B or C airspace, CTA or TMA are
VFR frequencies. Airports which have one of these categories of frequen-
cies also have APR and DEP which are IFR frequencies.
Where required, APR, DEP, CL B, CL C, CTA, and TMA frequencies are
sectorized. That is, a frequency may be used only within a certain range
of radials from a designated reference location. The format for displaying
the sectorization is to show the frequency first, followed by the identifier of
the associated reference point, fol-
lowed next by the associated altitude
restrictions. For example, figure 3-
154 shows that the Orlando
approach control frequency 121.10
MHz is used between the 311° radial
Chapter 3 Basic GPS Operation
3-56
Figure 3-154
