AIM

4/20/23

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21

Airport Operations

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

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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 instructions 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.

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15. Gate Holding Due to Departure Delays

a.

Pilots should contact ground control or clearance delivery prior to starting engines as gate hold procedures

will be in effect whenever departure delays exceed or are anticipated to exceed 15 minutes. The sequence for
departure will be maintained in accordance with initial call up unless modified by flow control restrictions. Pilots
should monitor the ground control or clearance delivery frequency for engine startup advisories or new proposed
start time if the delay changes.

b.

The tower controller will consider that pilots of turbine

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powered aircraft are ready for takeoff when they

reach the runway or warm

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up block unless advised otherwise.

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16. VFR Flights in Terminal Areas

Use reasonable restraint in exercising the prerogative of VFR flight, especially in terminal areas. The weather
minimums and distances from clouds are minimums. Giving yourself a greater margin in specific instances is
just good judgment.

a. Approach Area.

Conducting a VFR operation in a Class B, Class C, Class D, and Class E surface area

when the official visibility is 3 or 4 miles is not prohibited, but good judgment would dictate that you keep out
of the approach area.

b. Reduced Visibility.

It has always been recognized that precipitation reduces forward visibility.

Consequently, although again it may be perfectly legal to cancel your IFR flight plan at any time you can proceed
VFR, it is good practice, when precipitation is occurring, to continue IFR operation into a terminal area until you
are reasonably close to your destination.

c. Simulated Instrument Flights.

In conducting simulated instrument flights, be sure that the weather is

good enough to compensate for the restricted visibility of the safety pilot and your greater concentration on your
flight instruments. Give yourself a little greater margin when your flight plan lies in or near a busy airway or close
to an airport.

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17. VFR Helicopter Operations at Controlled Airports

a. General.

1.

The following ATC procedures and phraseologies recognize the unique capabilities of helicopters and

were developed to improve service to all users. Helicopter design characteristics and user needs often require