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Instrument Flying Handbook
Emergency Operations
Unforecasted Adverse Weather

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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

St. Elmo’s Fire
Figure 11-1. St. Elmo's Fire is harmless but may affect both communications and navigation radios, especially the lower frequencies such as those used on the ADF.

Precipitation Static
Precipitation static, often referred to as P-static occurs
when accumulated static electricity is discharged from the
extremities of the aircraft. This discharge has the potential
to create problems for the instrument pilot. These problems
range from the serious, such as erroneous magnetic compass
readings and the complete loss of very high frequency (VHF)
communications to the annoyance of high-pitched audio
squealing and St. Elmo's fire. [Figure 11-1]

Precipitation static is caused when an aircraft encounters
airborne particles during flight (e.g., rain or snow),
and develops a negative charge. It can also result from
atmospheric electric fields in thunderstorm clouds. When
a significant negative voltage level is reached, the aircraft
discharges it, which can create electrical disturbances. This
electrical discharge builds with time as the aircraft flies in
precipitation. it is usually encountered in rain, but snow can
cause the same effect. As the static buildup increases, the
effectiveness of both communication and navigation systems
decreases to the point of potential instability.

To reduce the problems associated with P-static, the pilot
should ensure the aircraft's static wicks are properly maintained
and accounted for. Broken or missing static wicks should he
replaced before an instrument flight. [Figure 11-2]

static wick

Figure 11-2. One example of a static wick installed on aircraft
control surface to bleed off static charges built up during flight.
This will prevent static buildup and St. Elmo 's fire by allowing
the static electricity to dissipate harmlessly.