Recentemente, fui informado por um amigo que, assim que a RNP para uma abordagem estiver abaixo do padrão 1.0 / 0.3nm, é necessário que seja o RNP AR.
Pelo menos aqui na Austrália, um segmento curvo em qualquer lugar da abordagem o qualificará como RNP AR, mesmo se o RNP for 1.0 / 0.3nm.
Existe uma regra rígida e rápida para o RNP AR?
No ICAO DOC 9905 (Manual de Design de Procedimentos Necessários para Autorização de Desempenho da Navegação Necessária), você pode encontrar a seguinte definição no Capítulo 2.1
RNP APCH versus RNP AR APCH
2.1.1 RNP APCH is defined as an RNP approach procedure that requires a lateral TSE of +/-1 NM in the initial, intermediate and missed approach segments (MAS) and a lateral TSE of ±0.3 NM in the FAS. Guidance on implementing RNP APCH operations can be found in the PBN Manual, Volume II, Chapter 5, Implementing RNP APCH.
2.1.2 RNP AR APCH is defined as an RNP approach procedure that requires a lateral TSE as low as ±0.1 NM on any segment of the approach procedure. RNP AR APCH procedures also require that a specific vertical accuracy be maintained as detailed in the PBN Manual, Volume II, Part B, Chapter 6. The datum crossing point (DCP) for RNP AR procedures is the point located above the landing threshold point (LTP) or the fictitious threshold point (FTP). The RNP AR APCH criteria apply only to those aircraft and operators complying with specified additional certification, approval and training requirements. RNP AR APCH procedures are only published where significant operational advantages can be achieved while preserving or improving safety of operation. The RNP AR certification and approval requirements are contained in the PBN Manual. For the purposes of applying the criteria contained in this manual, RNP AR procedure obstacle protection is associated with RNP navigation accuracy requirements. The RNP navigation accuracy requirement is used to determine the area semi-width value (in NM) of a protection area associated with a segment of an instrument procedure.
Portanto, sim, qualquer procedimento abaixo do padrão 1.0 / 0.3 NM é definido como RNP AR.
Normalmente, você não encontrará segmentos curvos (curvas de RF) em um gráfico RNP APCH, pois esses segmentos exigem um FMS recente, conforme observado no ICAO DOC 8168 Vol. II Parte III Apêndice do Capítulo 5.
Note 5.— RF may only be used for RNP procedures flown by aircraft equipped with systems that are compatible with ARINC 424-17, or later.
Nesses casos, o gráfico será divulgado com RF necessário.