AIM

8/15/19

4

−

3

−

20

Airport Operations

TBL 4

−

3

−

1

Airport Traffic Control Tower Light Gun Signals

Meaning

Color and Type of Signal

Movement of Vehicles,

Equipment and Personnel

Aircraft on the Ground

Aircraft in Flight

Steady green

Cleared to cross, proceed or go

Cleared for takeoff

Cleared to land

Flashing green

Not applicable

Cleared for taxi

Return for landing (to be
followed by steady green at the
proper time)

Steady red

STOP

STOP

Give way to other aircraft and
continue circling

Flashing red

Clear the taxiway/runway

Taxi clear of the runway in use

Airport unsafe, do not land

Flashing white

Return to starting point on airport Return to starting point on airport Not applicable

Alternating red and green

Exercise extreme caution

Exercise extreme caution

Exercise extreme caution

4

−

3

−

14. Communications

a.

Pilots 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.

REFERENCE

−

AIM, Paragraph 4

−

1

−

13 , Automatic Terminal Information Service

(ATIS)

b.

The 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.

c.

The 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
aircraft on the ground and between the tower and
utility vehicles on the airport, provide a clear VHF
channel for arriving and departing aircraft. They are
used for issuance of taxi information, clearances, and
other necessary contacts between the tower and
aircraft or other vehicles operated on the airport. A
pilot who has just landed should not change from the

tower frequency to the ground control frequency until
directed to do so by the controller. Normally, only one
ground control frequency is assigned at an airport;
however, at locations where the amount of traffic so
warrants, a second ground control frequency and/or
another frequency designated as a clearance delivery
frequency, may be assigned.

d.

A controller may omit the ground or local

control frequency if the controller believes the pilot
knows which frequency is in use. If the ground
control frequency is in the 121 MHz bandwidth the
controller may omit the numbers preceding the
decimal point; e.g., 121.7, “CONTACT GROUND
POINT SEVEN.” However, if any doubt exists as to
what frequency is in use, the pilot should promptly
request the controller to provide that information.

e.

Controllers will normally avoid issuing a radio

frequency change to helicopters, known to be
single

−

piloted, which are hovering, air taxiing, or

flying near the ground. At times, it may be necessary
for pilots to alert ATC regarding single pilot
operations to minimize delay of essential ATC
communications. Whenever possible, ATC instruc-
tions will be relayed through the frequency being
monitored until a frequency change can be
accomplished. You must promptly advise ATC if you
are unable to comply with a frequency change. Also,
you should advise ATC if you must land to
accomplish the frequency change unless it is clear the
landing will have no impact on other air traffic;
e.g., on a taxiway or in a helicopter operating area.