| Home | Privacy | Contact |

Instrument Flying Handbook
Flight Instruments
Pitot Static Instruments

| First | Previous | Next | Last |

Instrument Flying
Handbook

Preface

Table of Contents

Chapter 1. Human Factors
Chapter 2. Aerodynamic Factors
Chapter 3. Flight Instruments
Chapter 4. Section I
Airplane Attitude Instrument
Flying
Using Analog Instrumentation
Chapter 4. Section II
Airplane Attitude Instrument
Flying
Using an Electronic Flight
Display

Chapter 5. Section I
Airplane Basic
Flight Maneuvers
Using Analog Instrumentation
Chapter 5. Section II
Airplane Basic
Flight Maneuvers
Using an Electronic Flight
Display

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
Operations

Sensitive Altimeter Components.
Figure 3-3. Sensitive Altimeter Components.

A sensitive altimeter is one with an adjustable barometric scale
allowing the pilot to set the reference pressure from which the
altitude is measured. This scale is visible in a small window
called the Kollsman window. A knob on the instrument adjusts
the scale. The range of the scale is from 28.00" 10 31.00'
inches of mercury (Hg), or 948 to 1,050 millibars.

Rotating the knob changes both die barometric scale and
the altimeter pointers in such a way that a change in the
barometric scale of 1" Hg changes the pointer indication
by 1,000 feet. This is the standard pressure lapse rate
below 5,000 feet. When the barometric scale is adjusted
to 29.92" Hg or 1,013.2 millibars, the pointers indicate the
pressure altitude. The pilot displays indicate altitude by
adjusting the barometric scale to the local altimeter setting.
The altimeter then indicates the height above the existing
sea level pressure.

Altimeter Errors
A sensitive altimeter is designed to indicate standard changes
from standard conditions, but most flying involves errors
caused by nonstandard conditions and the pilot must be able
to modify the indications to correct for these errors. There
are two types of errors: mechanical and inherent.

Mechanical
A preflight check to determine the condition of an altimeter
consists of setting the barometric scale to die local altimeter
setting. The altimeter should indicate the surveyed elevation
of the airport. If the indication is off by more than 75 feet from
the surveyed elevation, the instrument should be referred
to a certificated instrument repair station for recalibration.
Differences between ambient temperature and/or pressure
causes an erroneous indication on the altimeter.

A sensitive altimeter is one with an adjustable barometric scale
Figure 3-4. Three-Pointer Altimeter, Figure 3-5. Drum-Type Altimeter.

 

3-4