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Instrument Flying Handbook
The Air Traffic Control System
Approach Control Facility and Approach Control Advances

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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

Generally, when weather disrupts the flow of air traffic,
greater workload demands are placed on the controller.
Requests for deviations from course and other services
should be made as far in advance as possible to better assure
the controller's ability to approve these requests promptly.
When requesting approval to detour around weather activity,
include the following information to facilitate the request:

1. The proposed point where detour commences;

2. The proposed route and extent of detour (direction
and distance);

3. The point where original route will he resumed;

4. Flight conditions (IMC or VMC);

5. Whether the aircraft is equipped with functioning
airborne radar; and

6. Any further deviation that may become necessary.

To a large degree, the assistance that might be rendered
by ATC depends upon the weather information available
to controllers. Due to the extremely transitory nature of
hazardous weather, the controllers displayed precipitation
information may be of limited value.

Obtaining IFR clearance or approval to circumnavigate
hazardous weather can often he accommodated more readily
in the en route areas away from terminals because there
is usually less congestion and, therefore, greater freedom
of action, in terminal areas, the problem is more acute
because of traffic density. ATC coordination requirements,
complex departure mid arrival routes, and adjacent airports.
As a consequence, controllers are less likely to be able to
accommodate all requests for weather detours in a terminal
area. Nevertheless, pilots should not hesitate to advise
controllers of any observed hazardous weather and should
specifically advise controllers if they desire circumnavigation
of observed weather.

Pilot reports (PIREPs) of flight conditions help define the
nature and extent of weather conditions in a particular area.
These reports are disseminated by radio and electronic means
to other pilots. Provide PIREP information to ATC regarding
pertinent flight conditions, such as:

1. Turbulence;

2. Visibility

3. Cloud tops and bases; and

4. The presence of hazards such as ice, hail, and

Approach Control Facility

An approach control facility is a terminal ATC facility
that provides approach control service in the terminal area.
Services are provided for arriving and departing VFR and
IFR aircraft and, on occasion, en route aircraft. In addition,
for airports with parallel runways with ILS or LDA
approaches, the approach control facility provides monitoring
of the approaches.

Approach Control Advances

Precision Runway Monitor (PRM)
Over the past few years, a new technology has been installed
at airports that permits a decreased separation distance
between parallel runways. The system is called a Precision
Runway Monitor (PRM) and is comprised of high-update
radar, high-resolution ATC displays, and PRM-certified
controllers. [Figure 9-14]

High Resolution ATC Displays
Figure 9-14. High Resolution ATC Displays Used in PRM.

Precision Runway Monitor (PRM) Radar
The PRM uses a Monopulse Secondary Surveillance Radar
(MSSR) that employs electronically scanned antennas.
Because the PRM has no scan rate restrictions, it is capable
of providing a faster update rate (up to 0.5 second) over
conventional systems, thereby providing better target
presentation in terms of accuracy, resolution, and track
prediction. The system is designed to search, track, process,
and display SSR-equipped aircraft within airspace of over
30 miles in range and over 15,000 feet in elevation. Visual
and audible alerts are generated to warn controllers to take
corrective actions.