DOC AIRBUS | AMM A320FSTANDBY DATA : ALTITUDE AND AIRSPEED - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. General
One standby airspeed indicator, one standby altimeter and one metric altimeter are directly connected to the standby pitot and static sources. Each indicator is contained in a 2 ATI case (ARINC 408) and installed on the center instrument panel. The standby circuit can be drained by means of a water drain.
** ON A/C NOT FOR ALL One standby airspeed indicator, one standby altimeter and one metric altimeter are directly connected to the standby pitot and static sources. Each indicator is contained in a 2 ATI case (ARINC 408) and installed on the center instrument panel. The standby circuit can be drained by means of a water drain.
2. Component Location
** ON A/C NOT FOR ALL 
Standby Data - Altitude and Airspeed - Component Location| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 3FN | ALTM-STANDBY | 401VU | 211 | 34-21-22 | |
| 9FN | IND-STANDBY AIRSPEED | 401VU | 211 | 34-21-26 | |
| 15FN | ALTIMETER-METRIC | 401VU | 211 | 34-21-25 | |
3. System Description
A. Standby Altimeter
The standby altimeter is supplied with static pressure by the standby air data system to indicate the barometric altitude of the aircraft in feet.
The barometric altitude is displayed by means of:
The standby altimeter is supplied with static pressure by the standby air data system to indicate the barometric altitude of the aircraft in feet.
The barometric altitude is displayed by means of:
- a pointer (4) performing one revolution of the dial for 1000 feet
- a display counter (5) made up of two drums displaying respectively the tens of thousands and the thousands of feet.
When the altitude is below 10,000 feet, the figure zero of the left drum is replaced by black and white stripes. The figure nine is replaced by an orange fire stripped zone.
the altitude dial (6) is calibrated from 0 to 1000 feet with 20 feet graduations - the baro correction (2) is displayed on a counter graduated in hecto Pascal
- a knob (1) located at the L corner of the indicator enables the display of the reference baro correction in the range of 750 to 1050 hPa.
- four manually adjustable white bugs (3) are provided for manual altitude setting.
To improve accuracy, 28VDC supplies the internal vibrator of the standby altimeter through a landing gear relay.
In straight and level flight, with the internal vibrator operating, the standby altimeter gives the following accuracy:
plus or minus 20 ft. at sea level
plus or minus 40 ft. at 6000 ft.
plus or minus 80 ft. at 10,000 ft.
plus or minus 130 ft. at 20,000 ft.
plus or minus 205 ft. at 35,000 ft.
NOTE: On the ground, with the internal vibrator not supplied, the above figures may be plus or minus 300ft.
Integral lighting supplied with external 5VAC is provided to illuminate the presentation.
Integral lighting supplied with external 5VAC is provided to illuminate the presentation.
B. Standby Airspeed Indicator
The standby airspeed indicator contains a capsule-operated mechanism which measures the pitot/static pressure differential from the standby air data system and provides airspeed indication in terms of knots with the following accuracy:
The standby airspeed indicator contains a capsule-operated mechanism which measures the pitot/static pressure differential from the standby air data system and provides airspeed indication in terms of knots with the following accuracy:
- plus or minus 3 kts for VC < 200 kts
- plus or minus 4 kts for 200 kts < VC < 300 kts
- plus or minus 5 kts for 300 kts < VC < 450 kts.
- a pointer (9) which moves on a dial (7) graduated between 60 kts and 450 kts. The scale is linear from 60 kts to 250 kts with 5 kts graduations and from 250 kts to 450 kts with 10 kts graduations.
- four manually adjustable white bugs (8) provided for manual speed setting.
C. Metric Altimeter
The metric altimeter is supplied with static pressure by the standby air data system to indicate the barometric altitude of the aircraft in meters with the following accuracy:
plus or minus 15 m at the sea level
plus or minus 20 m at 2000 m
plus or minus 35 m at 6000 m
plus or minus 40 m at 8000 m
plus or minus 45 m at 10,000 m
plus or minus 60 m at 15,000 m
The barometric altitude is displayed by means of:
The metric altimeter is supplied with static pressure by the standby air data system to indicate the barometric altitude of the aircraft in meters with the following accuracy:
plus or minus 15 m at the sea level
plus or minus 20 m at 2000 m
plus or minus 35 m at 6000 m
plus or minus 40 m at 8000 m
plus or minus 45 m at 10,000 m
plus or minus 60 m at 15,000 m
The barometric altitude is displayed by means of:
- a pointer (10) performing one revolution of the dial for 1000 meters.
- a display counter (11) made up of two drums displaying respectively the tens of thousands, and the thousands of meters.
- the altitude dial (12) is calibrated from 0 to 1000 meters with 50 meters graduations.
- the baro correction (14) is displayed on a counter graduated in hecto Pascal.
- a knob (13) located at the L corner of the indicator enables the display of the reference baro correction in the range of 870 to 1050 hPa.
Integral lighting supplied with external 5VAC is provided to illuminate the presentation.