INSTRUMENTS AND RECORDERS, AIR DATA SYSTEM
Description
Aircraft Operations Manual
12/1.1
PAGE
5
Apr 01/15
Airspeed indicators
The electromechanical airspeed indicator is sup-
plied with information from the ADC regarding indi-
cated airspeed (IAS) and Maximum operating
speed (V
MO
). The speed information is converted
and displayed by two pointers which indicates IAS
and V
MO
against a non
−
linear scale for maximum
accuracy.
Both airspeed indicators are provided with airspeed
reference bugs that can be set as reminders. As an
option a servodriven bug can be included in the L
IAS indicator. The bug is used to select speed for
the FD/AP when flying in IAS mode. Also see 3.1
AUTOFLIGHT. The set value also goes to a circuit-
ry in the indicator determining the difference be-
tween selected and actual speed. This difference is
displayed as a Fast
−
Slow deviation indication on
the EADI.
The pneumatic airspeed indicators are connected
directly to the pitot and static pressures. The right
airspeed indicator has two pointers indicating IAS
and V
MO
. The indicator is also provided with air-
speed reference bugs that can be set as reminders.
The indicator also gives overspeed warning as a
backup for the ADC overspeed warning. The stand-
by airspeed indicator gives only IAS indication.
Vertical speed indicator
The electromechanical vertical speed indicator
displays vertical speed which has been determined
and supplied by the ADC. The pneumatic indicator
converts change in static pressure into a proportion-
al vertical speed.
Vertical navigation indicator (Optional)
This instrument has two functions:
−
To serve as an indicator displaying vertical speed
as determined by the ADC.
−
To compute data for vertical navigation. These
data are either used to feed the FD/AP for auto-
matic capture of the vertical path or to be dis-
played to aid in a manual capture of the aiming
point.
Vertical navigation is described in AOM 3.1 AUTO-
FLIGHT.
SAT/TAS indication
Static Air Temperature and True Air Speed are de-
termined by the ADC and displayed on the EHSI’s.
Altitude Preselector Alerter
The Altitude Preselector Alerter (APA) system alerts
the flight crew when the aircraft is approaching, or
deviating from, a selected altitude. The alert
announcement is both aural and visual.
The APA is supplied with barometer corrected alti-
tude from the servo altimeter. The barometer
corrections made by the altimeter baroset knob thus
also affects the APA. The altitude for which an alert
announcement is desired is set with the ALT SET
knob on the altitude preselector on the glareshield
panel. The aural warning is produced by the WEU.
The system is interconnected with the FD/AP to
provide selected altitude for the ALTS mode.
Also see AOM 3, AUTOFLIGHT.
Airspeed Sensor
The airspeed sensor is supplied from the standby
pitot/static tube. The sensor converts the pressures
into electrical IAS signals which it provides to the
AHRS and Rudder Limiter systems. The Rudder
Limiter system uses this IAS as an accurancy
check of the Airdata computer provided IAS signal.
