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Instrument Flying Handbook
The Air Traffic Control System
Communication Procedures and Facilities

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Instrument Flying


Table of Contents

Chapter 1. Human Factors
Chapter 2. Aerodynamic Factors
Chapter 3. Flight Instruments
Chapter 4. Section I
Airplane Attitude Instrument
Using Analog Instrumentation
Chapter 4. Section II
Airplane Attitude Instrument
Using an Electronic Flight

Chapter 5. Section I
Airplane Basic
Flight Maneuvers
Using Analog Instrumentation
Chapter 5. Section II
Airplane Basic
Flight Maneuvers
Using an Electronic Flight

Chapter 6. Helicopter
Attitude Instrument Flying

Chapter 7. Navigation Systems
Chapter 8. The National
Airspace System

Chapter 9. The Air Traffic
Control System

Chapter 10. IFR Flight
Chapter 11. Emergency

When reporting ready to copy an IFR clearance before the
strip has been received from the Center computer, pilots
are advised "clearance on request." The controller initiates
contact when it has been received. This time can be used for
taxi and pre-takeoff checks.

The local controller is responsible for operations in the Class
D airspace and on the active runways. At some towers,
designated as IFR towers, the local controller has vectoring
authority. At visual flight rules (VFR) towers, the local
controller accepts inbound IFR flights from the terminal radar
facility and cannot provide vectors. The local controller also
coordinates flights in the local area with radar controllers.
Although Class D airspace normally extends 2,500 feet above
field elevation, towers frequently release the top 500 feet to
the radar controllers to facilitate over flights. Accordingly,
when a flight is vectored over an airport at an altitude that
appears to enter the tower controller's airspace, there is no
need to contact the tower controller, all coordination is
handled by ATC.

The departure radar controller may be in the same building
as the control tower, but it is more likely that the departure
radar position is remotely located. The tower controller will
not issue a takeoff clearance until the departure controller
issues a release.

Terminal Radar Approach Control (TRACON)
TRACONs are considered terminal facilities because they
provide the link between the departure airport and the en route
structure of the NAS. Terminal airspace normally extends 30
nautical miles (NM) from the facility, with a vertical extent

Combined Radar and Beacon Antenna.
Figure 9-7. Combined Radar and Beacon Antenna.

of 10,000 feet; however, dimensions vary widely. Class B
and Class C airspace dimensions are provided on aeronautical
charts. At terminal radar facilities the airspace is divided
into sectors, each with one or more controllers, and each
sector is assigned a discrete radio frequency. All terminal
facilities are approach controls and should be addressed
as "Approach" except when directed to do otherwise (e.g.,
"Contact departure on 120.4").

Terminal radar antennas are located on or adjacent to the
airport. Figure 9-7 shows a typical configuration. Terminal
controllers can assign altitudes lower than published
procedural altitudes called minimum vectoring altitudes
(MVAs). These altitudes are not published or accessible to
pilots, but are displayed at the controller's position, as shown
in Figure 9-8. However, when pilots are assigned an altitude
that seems to be too low, they should query the controller
before descending.

When a pilot accepts a clearance and reports ready for takeoff,
a controller in the tower contacts the TRACON for a release.
An aircraft is not cleared for takeoff until the departure
controller can fit the flight into the departure flow. A pilot may
have to hold for release. When takeoff clearance is received,
the departure controller is aware of the flight and is waiting
for a call. All of the information the controller needs is on
the departure strip or the computer screen there is no need to
repeat any portion of the clearance to that controller. Simply
establish contact with the facility when instructed to do so by
the tower controller. The terminal facility computer picks up
the transponder and initiates tracking as soon as it detects the
assigned code. For this reason, the transponder should remain
on standby until takeoff clearance has been received.

Minimum Vectoring Altitude Chart.
Figure 9-8. Minimum Vectoring Altitude Chart.