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Instrument Flying Handbook
IFR Flight
Instrument Weather flying

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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

In-flight turbulence can range from occasional light humps
to extreme airspeed and attitude variations that make aircraft
control difficult. To reduce the risk factors associated with
turbulence, pilots must learn methods of avoidance, as
well as piloting techniques for dealing with an inadvertent

Turbulence avoidance begins with a thorough preflight weather
briefing. Many reports and forecasts are available to assist
the pilot in determining areas of potential turbulence. These
include the Severe Weather Warning (WW). SIGMET (WS),
Convective SIGMET (WST), AIRMET (WA), Severe Weather
Outlook (AC), Center Weather Advisory (CWA), Area Forecast
(FA). and Pilot Reports (UA or PIREPs). Since thunderstorms
are always indicative of turbulence, areas of known and forecasted
thunderstorm activity will always be of interest to the pilot. In
addition, clear air turbulence (CAT) associated with jet steams,
strong winds over rough terrain, and fast moving cold fronts are
good indicators of turbulence.

Pilots should be alert while in flight for the signposts of
Turbulence. For example, clouds with vertical development
such as cumulus, towering cumulus, and cumulonimbus are
indicators of atmospheric instability and possible turbulence.
Standing lenticular clouds lack vertical development but
indicate strong mountain wave turbulence. While en route,
pilots can monitor hazardous in-flight weather advisory

service (HIWAS) broadcast for updated weather advisories,
or contact the nearest AFSS or En Route Flight Advisory
Service (EFAS) for the latest turbulence-related PIREPs.

To avoid turbulence associated with strong thunderstorms,
circumnavigate cells by at least 20 miles. Turbulence may
also be present in the clear air above a thunderstorm. To
avoid this, fly at least 1,000 feet above the top for every 10
knots of wind at that level, or fly around the storm. Finally,
do not underestimate the turbulence beneath a thunderstorm.
Never attempt to fly under a thunderstorm. The possible
results of turbulence and wind shear under the storm could
be disastrous.

When moderate to severe turbulence is encountered, aircraft
control is difficult, and a great deal of concentration is
required to maintain an instrument scan. [Figure 10-14] Pilots
should immediately reduce power and slow the aircraft to
the recommended turbulence penetration speed as described
in the POH/AFM. To minimize the load factor imposed on
the aircraft, the wings should he kept level and the aircraft's
pitch attitude should be held constant. The aircraft is allowed
to fluctuate up and down, because maneuvering to maintain
a constant altitude only increases the stress on the aircraft.
If necessary, the pilot should advise ATC of the fluctuations
and request a block altitude clearance. In addition, the power
should remain constant at a setting that will maintain the
recommended turbulence penetration airspeed.

Maintaining an Instrument .scan in severe turbulence can be difficult.
Figure 10-14. Maintaining an Instrument scan in severe turbulence can be difficult.