Are You Ready for Performance-Based Navigation (Part 2)

Mario Pierobon  |  15th October 2015
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Mario Pierobon
Mario Pierobon

Mario Pierobon holds a Master’s Degree in Air Transportation Management from City University London,...

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Performance Based Navigation BizAv

The concept of Performance Based Navigation (PBN) gains traction with more PBN procedures being published worldwide. Mario Pierobon introduces the variety of PBN specifications available and describes the benefits to Business Aviation.

Last month we clarified that Performance Based Navigation (PBN) specifications are articulated in two main categories: RNAV (area navigation) and RNP (required navigation performance), and established that RNP has the additional requirement for on-board performance monitoring and alerting. By looking at availability of navigation specifications under both the RNAV and RNP categories, it is possible to appreciate how the PBN concept, and its inherent operational flexibility, is available for all phases of flight operations.

Per the latest version of the ICAO PBN Manual (dated early 2013), there are 11 navigation specifications: four of these apply to RNAV and seven apply to RNP.

Documented in Volume II of the PBN Manual, each of these specifications is roughly 20 pages in length and contains core and contextual material. Core material relating to the navigation specification includes descriptions as to the performance (accuracy, integrity and continuity) required from the RNAV system, the functionalities needed to meet the requirements of the navigation application, the approval process, aircraft eligibility and operational approval.

“The PBN concept suggests that RNAV specifications are effectively legacy specifications and that no new RNAV specifications will be developed,” notes Eurocontrol. “Indeed, PBN’s sights are firmly set on RNP which relies primarily on the use of satellite technologies. This explains why all the new navigation specifications in the 2013 update to the PBN Manual are RNP specifications.”

Table A offers an overview of the navigation specs included in ICAO’s PBN Manual. The numbers reported refer to the lateral total system error and the along-track error, which must be (for example) within ±10 NM for at least 95% of the total flight time for RNAV 10 situations.

The content of the navigation specifications is normally reported in its entirety in advisory circulars (ACs) issued by the US FAA and acceptable means of compliance (AMCs) issued by EASA. These documents establish what operators must do to comply with the specified PBN airworthiness, operational and training requirements.

Application to BizAv?

Business Aviation operators should pay the most attention to PBN navigation specifications applicable to the approach phase of flight. “Business aircraft tend to operate away from big airports normally used by the airlines,” notes Captain Marcel Martineau, a flight operations consultant with whom we spoke. “This is the advantage of having your own aircraft and being able to land at thousands of airports in the US alone. The flexibility is clear.

“If [business jets] have a navigation system capable of receiving satellite-based augmentation (SBAS), operators can use the SBAS-capable GPS to meet very precise navigational accuracy independent of ground based systems.”

Augmentation is a method of improving the on-board navigation system’s accuracy, reliability and availability, through the integration of external information into the internal calculation process.

Examples of regional SBAS are the wide area augmentation system (WAAS), which is operational in the USA and Canada, and the European geostationary navigation overlay system (EGNOS), within Europe.

“This essentially means you can have all sorts of approaches at any remote airport and perform approaches where there are no ground facilities,” notes Martineau. “As you can imagine, this is of great advantage to business aircraft as many small airports are now publishing approaches without the need for ground facilities.

“It also significantly reduces operational cost by allowing operations at remote airports at low minima; reduces the environmental impact of aircraft (jet) operation; and increases the usefulness of business aircraft generally.”

With an increasing availability of PBN procedures at smaller airports, which typically lack extensive ground-based approach facilities, the benefits of upgrading to PBN capability is obvious. Next month we conclude this three-part series by clarifying technical, operational and training requirements to meet the PBN standards applicable to business aircraft operations.

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