AMC1Â ACNS.C.PBN.535Â Resolution and full-scale deflection of the vertical
deviation display
ED Decision 2022/008/R
Compliance with CSÂ ACNS.C.PBN.535 can be demonstrated
with one of the following ways:
(1)Â Â Â Â Installation of equipment with an ETSO authorisation against ETSO-C115d or ETSO-C146c supports the requirement of the CS, provided that the applicant ensures that the display characteristics comply with the CS.
(2)    Required navigation performance (RNP) systems that provide fixed vertical scaling should provide a non-numerical vertical deviation display with a full-scale deflection of ± 150 ft. In addition, the display should provide the flight crew with an easy way to readily identify a path deviation of 75 ft using the vertical deviation display alone, i.e. provide clear markings at + 75 ft and at – 75 ft.
Note: Subject to EASA’s agreement, the use of a scale of other than ± 150 ft may be accepted, provided that the scaling is suitable to control the aircraft on the intended path, and the 75-ft deviation can be easily identified by the flight crew. The applicant should provide a human factors and workload assessment, as well as relevant operating procedures that ensure that the aircraft’s deviation from the path can be monitored and bounded within the ± 75-ft interval, supporting this deviation.
(3)    Systems that use a type of angular vertical scaling other than the scaling defined in RTCA DO‑229D should meet the following:
(a)     The deviation scaling suitably supports the flight technical error (FTE) monitoring and bounding (± 75-ft deviation);
(b)Â Â Â Â The deviation limits are equivalent to the operational limits for glideslope deviations during an ILS approach.
To meet the primary safety objective of not exceeding an FTE of 75Â ft below the path to maintain obstacle clearance, it may be required to put a limitation on the length of the approach that the RNP system is able to support.
A vertical situation display is not considered to satisfy the requirements.
[Issue: CS-ACNS/2]
[Issue: CS-ACNS/4]
EASA aviation regulations for airborne navigation require precise vertical deviation displays in RNP systems. Displays must clearly show ±75ft deviations, aiding pilots in maintaining flight path accuracy. Alternative scaling may be acceptable with human factors assessment and procedures ensuring deviation monitoring within ±75ft. Angular scaling must support flight technical error monitoring.
* Summary by Aviation.Bot - Always consult the original document for the most accurate information.
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