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Instrument Flying Handbook
Airplane Basic Flight Maneuvers Using Analog Instrumentation
Straight-and-Level Flight

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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

Altitude Error; Lees Than 100 Feet.
Figure 5-9. Altitude Error; Lees Than 100 Feet.

Pitch Correction
Figure 5-10. Pitch Correction, Less Than 100 Feet One-Half Bar
Low to Correct Altitude Error.

Altitude Error, Greater Than 100 Feet.
Figure 5-11. Altitude Error, Greater Than 100 Feet.

Pitch Correction, Greater Than 100 Feet
Figure 5-12. Pitch Correction, Greater Than 100 Feet One Bar
Correction Initially.

pressure. As the needle returns to zero, relax the corrective
pressure. If control pressures have been smooth and light, the
needle reacts immediately and slowly, and the altimeter shows
little or no change of altitude. As a rate instrument, the VSI
requires consideration of lag characteristics.

Lag refers to the delay involved before the needle attains a
stable indication following a pitch change. Lag is directly
proportional to the speed and magnitude of a pitch change.
If a slow, smooth pitch change is initiated, the needle moves
with minimum lag to a point of deflection corresponding
to the extent of the pitch change, and then stabilizes as the
aerodynamic forces are balanced in the climb or descent,
A large and abrupt pitch change produces erratic needle
movement, a reverse indication, and introduces greater time
delay (lag) before the needle stabilizes. Pilots are cautioned
not to chase the needle when flight through turbulent
conditions produces erratic needle movements. The apparent
lag in airspeed indications with pitch changes varies greatly
among different airplanes and is due to the Lime required for
the airplane to accelerate or decelerate when the pitch attitude
is changed. There is no appreciable lag due to the construction
or operation of the instrument. Small pitch changes, smoothly
executed, result in an immediate change of airspeed.

When using the VSI as a rate instrument and combining it
with the altimeter and attitude indicator to maintain level
flight, a pilot should know that the amount the altimeter
needle moves from the desired altitude governs the rate which
should be used to return to that altitude. A rule of thumb is
to make an attitude change that will result in a vertical-speed
rate approximately doubles the error in altitude. For example,
if altitude is off by 100 feet, the rate of return to the desired
altitude should he approximately 200 feet per minute (fpm).
If it is off by more than 100 feet, the correction should
be correspondingly greater, but should never exceed the
optimum rate of climb or descent for the airplane at a given
airspeed and configuration.

A deviation of more than 200 fpm from the desired rate
of return is considered over controlling. For example, if
attempting to change altitude by 200 feet, a rate in excess of
400 fpm indicates over controlling.

When returning to an altitude, the VSI is the primary pitch
instrument. Occasionally, the VSI is slightly out of calibration
and may indicate a climb or descent when the airplane is in
level flight. If the instrument cannot be adjusted, take the
error into consideration when using it for pitch control. For
example, if the needle indicates a descent of 200 fpm while
in level flight, use this indication as the Zero position.