Aeronautical Information Manual (AIM), page 202

Index   201 -- Page 202 -- 203

beyond the departure end of the runway and within
300 feet of the traffic pattern altitude.

d. Many towers are equipped with a tower radar
display. The radar uses are intended to enhance the
effectiveness and efficiency of the local control, or
tower, position. They are not intended to provide
radar services or benefits to pilots except as they may

accrue through a more efficient tower operation. The

four basic uses are:
1. To determine an aircraft's exact location.

This is accomplished by radar identifying the VFR

aircraft through any of the techniques available to a
radar position, such as having the aircraft squawk
ident. Once identified, the aircraft's position and
spatial relationship to other aircraft can be quickly
determined, and standard instructions regarding VFR
operation in Class B, Class C, and Class D surface
areas will be issued. Once initial radar identification
of a VFR aircraft has been established and the
appropriate instructions have been issued, radar
monitoring may be discontinued; the reason being
that the local controller's primary means of
surveillance in VFR conditions is visually scanning
the airport and local area.

2. To provide radar traffic advisories. Radar
traffic advisories may be provided to the extent that
the local controller is able to monitor the radar
display. Local control has primary control responsibi-
lities to the aircraft operating on the runways, which
will normally supersede radar monitoring duties.

3. To provide a direction or suggested
heading. The local controller may provide pilots
flying VFR with generalized instructions which will
facilitate operations; e.g., "PROCEED SOUTH-
RUNWAY THREE ZERO," or provide a suggested
heading to establish radar identification or as an
advisory aid to navigation; e.g., "SUGGESTED
IDENTIFICATION." In both cases, the instructions
are advisory aids to the pilot flying VFR and are not
radar vectors.

Pilots have complete discretion regarding acceptance of
the suggested headings or directions and have sole
responsibility for seeing and avoiding other aircraft.

4. To provide information and instructions to
aircraft operating within Class B, Class C, and

Class D surface areas. In an example of this
situation, the local controller would use the radar to
advise a pilot on an extended downwind when to turn
base leg.

The above tower radar applications are intended to
augment the standard functions of the local control
position. There is no controller requirement to maintain

constant radar identification. In fact, such a requirement
could compromise the local controller's ability to visually
scan the airport and local area to meet FAA responsibilities
to the aircraft operating on the runways and within the

Class B, Class C, and Class D surface areas. Normally,
pilots will not be advised of being in radar contact since
that continued status cannot be guaranteed and since the
purpose of the radar identification is not to establish a link
for the provision of radar services.

e. A few of the radar equipped towers are
authorized to use the radar to ensure separation
between aircraft in specific situations, while still
others may function as limited radar approach
controls. The various radar uses are strictly a function
of FAA operational need. The facilities may be
indistinguishable to pilots since they are all referred
to as tower and no publication lists the degree of radar
use. Therefore, when in communication with a
tower controller who may have radar available, do
not assume that constant radar monitoring and
complete ATC radar services are being provided.

4-3-3. Traffic Patterns

a. At most airports and military air bases, traffic
pattern altitudes for propeller-driven aircraft gener-
ally extend from 600 feet to as high as 1,500 feet
above the ground. Also, traffic pattern altitudes for
military turbojet aircraft sometimes extend up to
2,500 feet above the ground. Therefore, pilots of en
route aircraft should be constantly on the alert for
other aircraft in traffic patterns and avoid these areas
whenever possible. Traffic pattern altitudes should be
maintained unless otherwise required by the
applicable distance from cloud criteria (14 CFR
Section 91.155). (See FIG 4-3-2 and FIG 4-3-3.)
Unless otherwise indicated, all turns in the traffic
pattern should be made to the left. On Sectional
Aeronautical and VFR Terminal Area Charts, right
traffic patterns are indicated at public-use and

joint-use airports by the abbreviation "RP" (for Right
Pattern), followed by the appropriate runway
number(s), at the bottom of the airport data block.

4-3-2 Airport Operations

Page 202 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   201 -- Page 202 -- 203