AIM
11/3/22
2.
Pilots are reminded that the surveillance radar
used by ATC does not provide altitude information
unless the aircraft is equipped with Mode C and the
radar facility is capable of displaying altitude
information.
b. Provisions of the Service
1.
Many factors, such as limitations of the radar,
volume of traffic, controller workload and commu-
nications frequency congestion, could prevent the
controller from providing this service. Controllers
possess complete discretion for determining whether
they are able to provide or continue to provide this
service in a specific case. The controller’s reason
against providing or continuing to provide the service
in a particular case is not subject to question nor need
it be communicated to the pilot. In other words, the
provision of this service is entirely dependent upon
whether controllers believe they are in a position to
provide it. Traffic information is routinely provided
to all aircraft operating on IFR flight plans except
when the pilot declines the service, or the pilot is
operating within Class A airspace. Traffic informa-
tion may be provided to flights not operating on IFR
flight plans when requested by pilots of such flights.
NOTE
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Radar ATC facilities normally display and monitor both
primary and secondary radar as well as ADS
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B, except
that secondary radar or ADS
−
B may be used as the sole
display source in Class A airspace, and under some
circumstances outside of Class A airspace (beyond
primary coverage and in en route areas where only
secondary and/or ADS
−
B is available). Secondary radar
and/or ADS
−
B may also be used outside Class A airspace
as the sole display source when the primary radar is
temporarily unusable or out of service. Pilots in contact
with the affected ATC facility are normally advised when
a temporary outage occurs; i.e., “primary radar out of
service; traffic advisories available on transponder or
ADS
−
B aircraft only.” This means simply that only aircraft
that have transponders and ADS
−
B installed and in use will
be depicted on ATC displays when the primary and/or
secondary radar is temporarily out of service.
2.
When receiving VFR radar advisory service,
pilots should monitor the assigned frequency at all
times. This is to preclude controllers’ concern for
radio failure or emergency assistance to aircraft under
the controller’s jurisdiction. VFR radar advisory
service does not include vectors away from
conflicting traffic unless requested by the pilot. When
advisory service is no longer desired, advise the
controller before changing frequencies and then
change your transponder code to 1200, if applicable.
Pilots should also inform the controller when
changing VFR cruising altitude. Except in programs
where radar service is automatically terminated, the
controller will advise the aircraft when radar is
terminated.
NOTE
−
Participation by VFR pilots in formal programs
implemented at certain terminal locations constitutes pilot
request. This also applies to participating pilots at those
locations where arriving VFR flights are encouraged to
make their first contact with the tower on the approach
control frequency.
c. Issuance of Traffic Information.
Traffic
information will include the following concerning a
target which may constitute traffic for an aircraft that
is:
1. Radar identified
(a)
Azimuth from the aircraft in terms of the
12 hour clock, or
(b)
When rapidly maneuvering civil test or
military aircraft prevent accurate issuance of traffic
as in (a) above, specify the direction from an aircraft’s
position in terms of the eight cardinal compass points
(N, NE, E, SE, S, SW, W, NW). This method must be
terminated at the pilot’s request.
(c)
Distance from the aircraft in nautical
miles;
(d)
Direction in which the target is proceed-
ing; and
(e)
Type of aircraft and altitude if known.
EXAMPLE
−
Traffic 10 o’clock, 3 miles, west-bound (type aircraft and
altitude, if known, of the observed traffic). The altitude may
be known, by means of Mode C, but not verified with the
pilot for accuracy. (To be valid for separation purposes by
ATC, the accuracy of Mode C readouts must be verified.
This is usually accomplished upon initial entry into the
radar system by a comparison of the readout to pilot stated
altitude, or the field elevation in the case of continuous
readout being received from an aircraft on the airport.)
When necessary to issue traffic advisories containing
unverified altitude information, the controller will issue the
indicated altitude of the aircraft. The pilot may upon
receipt of traffic information, request a vector (heading) to
avoid such traffic. The vector will be provided to the extent
possible as determined by the controller provided the
aircraft to be vectored is within the airspace under the
jurisdiction of the controller.
2. Not radar identified
Services Available to Pilots
4
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1
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