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Instrument Flying Handbook
Navigation Systems
Instrument Approach Systems

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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

Deflection of the GS needle indicates the position of the
aircraft with respect to the glide path. When the aircraft is
above the glide path, (lie needle is deflected downward. When
the aircraft is below the glide path, (he needle is deflected
upward. [Figure 7-40]

ILS Errors
The ILS and its components are subject to certain errors,
which are listed below. Localizer and GS signals are subject to
the same type of bounce from hard objects as space waves.

1. Reflection. Surface vehicles and even other aircraft
flying below 5,000 feet above ground level (AGL)
may disturb the signal for aircraft on the approach.

2. False courses. In addition to the desired course, GS
facilities inherently produce additional courses at
higher vertical angles. The angle of the lowest of these
false courses will occur at approximately 9°-12°. An
aircraft flying the LOC/GS course at a constant altitude
would observe gyrations of both the GS needle and GS
warning flag as the aircraft passed through the various
false courses. Getting established on one of these
false courses will result in either confusion (reversed
OS needle indications) or in the need for a very high

descent rate. However, if the approach is conducted
at the altitudes specified on the appropriate approach
chart, these false courses will not be encountered.

Marker Beacons
The very low power and directional antenna of the marker
beacon transmitter ensures that the signal will not be received
any distance from the transmitter site. Problems with signal
reception are usually caused by the airborne receiver not
being turned on, or by incorrect receiver sensitivity.

Some marker beacon receivers, to decrease weight and cost,
are designed without their own power supply. These units
utilize a power source from another radio in the avionics
stack, often the ADF. In some aircraft, this requires the
ADF to be turned on in order for the marker beacon receiver
to function, yet no warning placard is required. Another
source of trouble may he the "High/Low/Off' three-position
switch, which both activates the receiver and selects receiver
sensitivity. Usually, the "test" feature only tests to see if
the light bulbs in the marker beacon lights are working.
Therefore, in some installations, there is no functional way
for the pilot to ascertain the marker beacon receiver is actually
on except to fly over a marker beacon transmitter, and see if
a signal is received and indicated (e.g., audibly, and visually
via marker beacon lights).

GS receiver indication and aircraft
Figure 7-40. Illustrates a GS receiver indication and aircraft displacement. An analog system is on. the left and the same
indication on the Garmin PFD on the right.