On the final inbound approach, the track index should be set to the final approach course of the runway. A standard 3 ° approach path is indicated, when the top of the bird's tail is immediately below the horizon, and the bottom of the bird is immediately above the 5 ° nose down marker.
use of FPV in final approach
 
FINAL APPROACH
The bird is a very useful flight reference, because it provides the trajectory parameters, and
quickly warns the pilot of downburst. In addition, together with the GS MINI protection, it is an excellent indicator of shears or wind variations. The position of the "bird" in relation to the fixed aircraft symbol provides an immediate indication of the wind direction. Therefore, when approaching the minima, the pilot knows in which direction to search for the runway.
If the target approach speed symbol moves upward, this indicates that there is headwind gust. If the bird drifts to the right, this indicates that there is wind from the left.
Bird and target speed- wind interpretation
 
RELIABILITY
The FPV is computed from IRS data, therefore, it is affected by ADIRS errors. An error may be indicated by a small track error, usually of up to ± 2 °. This can be easily determined during the approach.
 

  SUPPLEMENTARY INFORMATION
FLYING REFERENCE
A318/A319/A320/A321
FLIGHT CREW TRAINING MANUAL 

The FPV is also computed from static pressure information. Therefore, the bird must be considered as not reliable, if altitude information is not reliable.
GO-AROUND
Criteria: SA
1 Applicable to: MSN 0045-0478, 0486-0499
For the go-around, the appropriate flight reference is the attitude, because go-around is a dynamic maneuver. Therefore, if the "bird" is on, the PF will ask the PNF to select HDG/VS, in order to recover the FD bars.
GO-AROUND
Criteria: 22-1058, P4319, SA
2 Applicable to: MSN 0480, 1668-4078
For the go-around, the appropriate flight reference is the attitude, because go-around is a dynamic maneuver. Therefore, when performing a go-around, regardless of the previously-selected flight reference, upon selection of TOGA, the FD bars are automatically restored in SRS/GA TRK modes, and the "bird" is automatically removed.
 

  SUPPLEMENTARY INFORMATION
NAVIGATION ACCURACY
A318/A319/A320/A321
FLIGHT CREW TRAINING MANUAL 

GENERAL
Applicable to: ALL
The primary function of the FMS is navigation i.e. to compute the aircraft's position as accurately as possible. The validity of all the others functions depends upon the accuracy of the FMS position.
The accuracy of the FMS navigation determines the flight crew's strategy for using the AP/FD modes, in addition to the ND display.
AIRCRAFT POSITION COMPUTATION
Applicable to: ALL
　
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