AMC1 ACNS.C.PBN.670 Vertical accuracy
ED Decision 2019/011/R
When the vertical position is provided by BARO-VNAV and the aircraft performs stabilised constant descent path, the RNP system should ensure that 99.7 % of the system error in the vertical position is equal to or less than the vertical error budget (VEB) attributed to the aircraft, as defined by (in feet):
Where:
ANPE = actual navigation performance error which can be computed as follows:
WPR = waypoint precision error which can be computed as follows:
FTE = flight technical error which can be assumed to be 75 feet with autopilot or flight director coupled.
ASE = altimetry system error which can be computed as follows:
Using:
— — ‘θ’ as the vertical navigation (VNAV) path angle;
— — ‘h’ as the height in feet of the local altimetry reporting station; and
— — ‘Δh’ as the height in feet of the aircraft above the reporting station.
Note: VEBaircraft contains the elements out of the minimum obstacle clearance (MOC) equation in Appendix 1 to ICAO Document 9905 ‘Required Navigation Performance Authorization Required Procedure Design Manual’, which are attributed to the aircraft. The applicant should not apply the other elements of the MOC equation, i.e. body geometry (bg) error or international standard atmosphere temperature deviation (isad), in support of demonstration of vertical accuracy.
[Issue: CS-ACNS/2]