The vertical deviation is available in approach only.
When a Non Precision Approach is selected on FMS F-PLN page for arrival, the V/DEV is
displayed if one of the following conditions is met:

.  
A/C is in the FMS approach area (5 NM to the first approach waypoint of the FMS F-PLN)

.  
The FMS approach phase is ACTIVATED

.  
FINAL mode is armed or engaged (APPR P/B pressed)

Full scale is ± 200ft, 1 dot = 100ft.
If the LS button is pressed on the FCU, the V/DEV scale is inhibited.

Prior to starting the final approach, the flight crew must cross check their altimeter setting and
altitude indications.

FAA requirement:
Altimeter Setting. Due to the reduced obstruction clearance inherent in RNP SAAAR instrument procedures, the flight crew must verify the most current airport altimeter is set prior to the final approach fix (FAF) but no earlier than the IAF.  Execution of an RNP SAAAR instrument procedure requires the current altimeter setting for the airport of intended landing. Remote altimeter settings are not allowed.
l. Altimeter Crosscheck.  The flight crew must complete an altimetry crosscheck ensuring both pilots’ altimeters agree within ±75 feet prior to the final approach fix (FAF) but no earlier than the IAF. If the altimetry crosscheck fails then the procedure must not be continued.
When the FINAL APP mode is active after the VIP (or FDP), at the latest at FAF, the crew must continuously monitor the V/DEV on PFD. The PNF should make a callout when the V/DEV is . dot below or . dot above the vertical flight path. A GA must be performed before . dot below the vertical flight path is reached. Corrective action when V/DEV is above the nominal flight path is a question of energy management in the approach, which is different from one approach to the other. The operator should adapt its procedure to each particular case.
7. RNP AR Operations and Training
Getting to grips with RNP AR

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7.2.4 RNP AR APPROACH AND MISSED APPROACH
The following information is to be considered in addition to the SOP.
7.2.4.1 APPROACH PREPARATION
In addition to the usual preparation, which is done during any flight, the following items need to be addressed:
.  
Check the weather report to confirm that OAT and surface wind as applicable are within limits for the RNP AR procedure.

.  
Review the aircraft status against the minimum equipment for RNP AR approach

.  
Confirm that the approach with the label RNV XY listed in the FMS is the intended RNP AR approach, and check it carefully with the approach chart, including the missed approach, check

o  Waypoint sequences

o  Altitude and speed constraints
　
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