Altitude Selector/Alerter
P/N 01279
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Pilot’s Operating
Handbook
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REVISIONS
Record of Revisions
Re ta in t h is record in th e f ro n t o f th is manua l. On rece ip t o f re v is io n s ,
insert revised pages in the manual and enter date inserted and initials.
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DATE
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REVNOREVISION
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List of Effective Pages
* The asterisk indicates the pages changed, added, or deleted by the
current chan
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1st Ed 26 Oct 00
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NOTES
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TABLE OF CONTENTS
REVISIONS 2
NOTES 3
TABLE OF CONTENTS 4
INTRODUCTION 5
ALTITUDE SELECTOR/ALERTER BLOCK DIAGRAM 6
ALTITUDE SELECTOR/ALERTER 7
Theory of Operation 7
Quick Reference 8
Important Points to Remember 8
Features and Functions 9
Self Test 9
Data (DTA) Entry - Operate 9
Baro Calibration 10
Vertical Speed (VS) Selector 11
Altitude (ALT) Select Function 14
Altitude Alert (ALR) Mode 14
Decision Height (DH) Alert Mode 15
Operation 16
Preflight 17
Inflight 19
Emergency Procedures 20
Lost Encoder Data 21
SYSTEM SPECIFICATIONS 22
LIST OF ACRONYMS 23
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INTRODUCTION
The Altitude/Vertical Speed Selector/Alerter, hereafter referred to as
Altitude Selector/Alerter, allows the pilot to preselect altitude and vertical speed. In addition to these basic functions, the selector provides an
Altitude (ALT) Alert Mode, a Decision Height (DH) Alert Mode, an Altitude Read-Out from the Encoder, barometric calibration in inches of
mercury or millibars, and other features. This handbook provides information on the features and functions of the Altitude Selector/Alerter and
operating instructions for its proper use.
The Altitude Selector/Alerter combines the computer and program-
mer units into a single panel mounted unit, which contains the display,
the operating switches and the computer electronics. The system was
designed to interface the S-TEC Autopilot with an altitude encoder/transponder providing a standard 100 ft increment altitude output.
Operation of the Altitude Selector/Alerter with the S-TEC Autopilot
is easy and straightforward. However, in order to achieve maximum benefit and to utilize all of the systems features, it is important to have a clear
understanding of the system and its operating characteristics, features and
functions. Please read this manual carefully before using the Altitude
Selector/Alerter.
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ALTITUDE SELECTOR/ALERTER
Theory of Operation
The Altitude Selector/Alerter (ASA) enables the pilot to preselect al-
titudes and rates of climb or descent to be used by the autopilot. The
ASA reads and decodes the altitude information from the altitude encoder. This decoded information is adjusted by the setting of the barometric (baro) calibration and then compared to a selected altitude setting.
When the information from the selected altitude matches the decoded
altitude information from the encoder, the altitude selector computer signals the autopilot to electrically engage the altitude hold mode of the
autopilot.
The Vertical Speed (VS) Selector provides an electrical output to the
autopilot pitch flight guidance computer that is proportional to the amplitude and polarity (direction) of the vertical speed. For example, a + 500
feet per minute (FPM) climb VS, would produce a plus (+) voltage in an
amount representing 500 FPM. This signal is not utilized by the autopilot until the VS Mode is engaged. At that time, the autopilot compares
the existing vertical speed with the selected vertical speed and maneuvers
the airplane to match these signals. The vertical speed selector portion of
the ASA can be disabled by pushing the “MAN” (Manual) switch which
will cause the autopilot to revert to its normal vertical speed command
system.
The Vertical Speed Selector portion of the ASA will function any
time the selector is showing a Vertical Speed and the Vertical Speed Mode
of the autopilot is selected. However, the Altitude Selector will function
only when the transponder and encoder are operating and when both the
VS and ALT Modes of the autopilot are selected.
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Data Entry - Liquid Crystal
Operate Switch Display Panel
Barometric Input Selector
Calibration Knob -Turn CW
(BARO) Mode to Increase, Pull
Switch for Decimals
Vertical Speed Selector and
Manual Mode Switches
Altitude Read Out/Altitude Selector, Alert (ALR)
and Decision Height (DH) Alert Mode Switches
ALTITUDE SELECTOR/ALERTER
Quick Reference
Important Points to Remember
1. Set Barometric calibration, Altitude and Vertical Speed following
initial self-test. System will be in data entry mode following self-test.
2. Push "DTA" to enter or change any data EXCEPT vertical speed VS. Once entered, push DTA to close the entry mode or the unit
cannot communicate your input/settings to the autopilot.
3. To activate pre-selected altitude and vertical speed, push both ALT
and VS buttons on the autopilot at the same time. This is confirmed
by the annunciation of both ALT and VS Modes on the autopilot.
4. For best accuracy relative to the target altitude, see "adjustment:
baro calibration" on page 10-11.
5. If you are unsure of the correct operation, turn off the Altitude
Selector/Alerter or push the MAN (Manual) button and revert to normal autopilot operation.
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