5. Visual Indicators at Airports Without an
Operating Control Tower
5.1At those airports without an operating control
tower, a segmented circle visual indicator system, if
installed, is designed to provide traffic pattern
information. The segmented circle system consists of
the following components:
5.1.1The Segmented Circle.Located in a position
affording maximum visibility to pilots in the air and
on the ground and providing a centralized location for
other elements of the system.
5.1.2The Wind Direction Indicator.A wind cone,
wind sock, or wind tee installed near the operational
runway to indicate wind direction. The large end of
the wind cone/wind sock points into the wind as does
the large end (cross bar) of the wind tee. In lieu of a
tetrahedron and where a wind sock or wind cone is
collocated with a wind tee, the wind tee may be
manually aligned with the runway in use to indicate
landing direction. These signaling devices may be
located in the center of the segmented circle and may
be lighted for night use. Pilots are cautioned against
using a tetrahedron to indicate wind direction.
5.1.3The Landing Direction Indicator.A tetrahedron
is installed when conditions at the airport
warrant its use. It may be used to indicate the direction
of landings and takeoffs. A tetrahedron may be
located at the center of a segmented circle and may be
lighted for night operations. The small end of the
tetrahedron points in the direction of landing. Pilots
are cautioned against using a tetrahedron for any
purpose other than as an indicator of landing
direction. Further, pilots should use extreme caution
when making runway selection by use of a
tetrahedron in very light or calm wind conditions as
the tetrahedron may not be aligned with the
designated calm−wind runway. At airports with
control towers, the tetrahedron should only be
referenced when the control tower is not in operation.
Tower instructions supersede tetrahedron indications.
5.1.4Landing strip indicators.Installed in pairs
as shown in the segmented circle diagram, and used
to show the alignment of landing strips.
5.1.5Traffic pattern indicators.Arranged in pairs
in conjunction with landing strip indicators and used
to indicate the direction of turns when there is a
variation from the normal left traffic pattern. If there
is no segmented circle installed at the airport, traffic
pattern indicators may be installed on or near the end
of the runway.
5.2Preparatory to landing at an airport without a
control tower, or when the control tower is not in
operation, the pilot should concern himself with the
indicator for the approach end of the runway to be
used. When approaching for landing, all turns must
be made to the left unless a traffic pattern indicator
indicates that turns should be made to the right. If the
pilot will mentally enlarge the indicator for the
runway to be used, the base and final approach legs
of the traffic pattern to be flown immediately become
apparent. Similar treatment of the indicator at the
departure end of the runway will clearly indicate the
direction of turn after takeoff.
5.3When two or more aircraft are approaching an
airport for the purpose of landing, the pilot of the
aircraft at the lower altitude has the right−of−way
over the pilot of the aircraft at the higher altitude.
However, the pilot operating at the lower altitude
should not take advantage of another aircraft, which
is on final approach to land, by cutting in front of, or
overtaking that aircraft.
6. Ground Control Frequencies
6.1Pilots of departing aircraft should communicate
with the control tower on the appropriate ground
control/clearance delivery frequency prior to starting
engines to receive engine start time, taxi and/or
clearance information. Unless otherwise advised by
the tower, remain on that frequency during taxiing
and runup, then change to local control frequency
when ready to request takeoff clearance.
NOTE−
Pilots are encouraged to monitor the local tower frequency
as soon as practical consistent with other ATC
requirements.
6.2The tower controller will consider that pilots of
turbine−powered aircraft are ready for takeoff when
they reach the runway or warm−up block unless
advised otherwise.
6.3The majority of ground control frequencies are in
the 121.6−121.9 MHz bandwidth. Ground control
frequencies are provided to eliminate frequency
congestion on the tower (local control) frequency and
are limited to communications between the tower and
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