Yak 18T Flight Operations Manual
Page 74 of 82
Disclaimer: This manual is to be used as a reference only, it is based on translated Yak 18T Flight Operations
Manuals and has not been approved by the Yakovlev Design Bureau or any other authority.
In flight the radio altimeter operates as follows –
•
when the aircraft climbs at a level of 750m and over, the indicator pointer of the
instrument goes beyond the scale black sector and it will be there until the aircraft
starts to descend to an altitude of 750m. At the moment the indicator pointer passes
the marker of the assigned altitude, a yellow warning light goes on at the instrument
and an audio signal will come to the telephones of the pilots
•
when the aircraft climbs at a level of 1200m and more, a red warning light built-into
the CHECKING control will be illuminated, it will extinguish when the aircraft
descends below 1200m
•
at altitudes of 750m and below the indicator pointer will show the absolute flight
altitude and at a further descent the radio altimeter warns when the desired altitude
will be achieved (a yellow lamp on the instrument lights on and an audio signal will
be heard in the telephones during 3-9 seconds). The light illuminates until the aircraft
lands and will extinguish after the power of has been off
CAUTION
It is not advisable to use readings when the bank and pitch angles exceed 30° -
•
switch the radio altimeter off after landing
•
if the radio altimeter failure Occurs in flight at a level of less than 750m, a red
warning light goes on in the altimeter
•
a fault signal, in this case switch the radio altimeter off
Instrument Approach Apparatus
General information
This apparatus is to be used by the homemade heating-glide path system and for
International Instrument Landing System (ILS) approaches.
This system provides signals of the aircraft diversion from the heading and glide path equi-
signal zones formed by the ground beacons and the inner and outer marker locators flyover
warning from the radio markers signals. The apparatus is controlled by the unit located on
the instrument panel from the left. The control unit accommodates the following controls:
power switch, frequency set control with a computer, operation mode switch ILS, apparatus
checking buttons.
By using the frequency set control, one can provide the operating frequency of the localizer
receiver over the range of 108.1-111.9 MHz with 0.2 MHz frequency spacing. Simultaneously,
tune the operating frequency of the glide-path receiver. The marker receiver, which operates
at a 75 MHz fixed frequency, is switched on in conjunction with the apparatus and has no
controls. The apparatus is fitted with built-in serviceability checking push-buttons, monitoring
is carried out from the control unit. The apparatus is supplied from a 27V DC aircraft
electrical wiring system. The power circuit is protected by the circuit breaker placed on the
switchboard.
Apparatus pre-flight switching-on and checking
To switch the apparatus on and to check it, proceed as follows –
•
switch the circuit breaker on at the switchboard
•
set the power switch on the control unit to the ON position
•
set the switch ILS to the position
•
using the frequency set control set 110.3 MHz on the counter
•
press the left CHECKING push-button. This must result in response of the heading
and glide-path magnetic indicators of the instrument the heading pointer will be
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