Performance-based navigation—a combination of RNAV and RNP
FAA’s plan to modify the NAS builds on PBN and its flexibility as a cornerstone.
Pro Pilot staff report
DCA will be one of the airports that benefit from advances in PBN and its operational efficiency.
Over the past decade FAA, with industry, has embarked on the redesign and modernization of the National Airspace System (NAS) with an eye to increasing efficiency in a highly saturated (and growing) structure and improving safety of operations.
Most recently dubbed NextGen, the program builds on advances in technology to provide better service to airspace users. The advent and widespread acceptance of GPS in commercial and business aircraft has been the engine that permits the advance of NextGen.
Born from the capability of GPS is the cornerstone of NextGen—performance-based navigation (PBN).
Overview and history
PBN is the umbrella under which both area navigation (RNAV) and required navigational performance (RNP) are found. RNAV capability has been around for decades and simply describes the ability of an aircraft to use ground-based navaids or GPS to fix its own position, create waypoints and follow a direct navigational route.
You may even remember early RNAV units that used VORs and allowed the pilot to “move” the VOR along a particular radial, at a particular distance, to create a waypoint. In fact this “leading edge” technology could be experienced 30 years ago in a brand new 1980 Beech Baron.
In its most basic form, RNP builds on RNAV by providing integrated monitoring of system performance and the ability to alert the crew when RNP is not possible. Combining RNAV and RNP, PBN is the basis on which NextGen will be implemented through 2025.
Although NextGen is a comprehensive solution that will span the next 2 decades and include other emerging technologies such as ADS-B and data communications, PBN is the foundation for the promised improvements in how air traffic is managed in the US and abroad.
Not just for heavy iron
NAS structure and onboard avionics capacity will help determine the level of service aircraft are capable of throughout the various phases of flight.
Some may dismiss PBN/RNAV/ RNP as strictly an air carrier concern. To do so would be shortsighted in the near term and a major strategic error in the long term. In its Roadmap for Performance Based Navigation, FAA clearly points out the importance of PBN for all users of the NAS. The agency goes further, saying that “General aviation (GA) continues to show strength and is expected to grow even stronger in the future.
Growth in GA aircraft is expected to increase point-to-point and direct routing, with the need for greater system flexibility to handle peaks in traffic demand, convective weather, military operations and security needs.”
In fact, FAA plans for GA to be a major player in NextGen and comments in the same report that “many business aviation aircraft are also (currently) capable of RNAV and basic RNP operations—approximately 75% being GPS equipped.” So PBN is the roadmap for all users of the NAS now and in the future.
Taking the leap
RNP approach capability will pay large dividends in terms of airport capacity and throughput.
Ignoring the escalating requirements for PBN would be a catastrophic mistake that could lead to onerous restrictions on flight operations for any air carrier or corporate flight department. To be clear, NextGen is here and PBN will be mandated.
Ignoring the hardware, software and training requirements to participate in PBN will severely limit an operator’s ability to fly when and where they want, at advantageous altitudes and preferred times of day. In the ultimate iteration of NextGen, aircraft unable to participate in PBN will, to all intents and purposes, be relegated to a similar category to light-sport airplanes.
This may be a strong statement, but just try to imagine operating today without a transponder. PBN timetables specify that, near the end of FAA’s “midterm plan,” some level of RNP capability will likely be required to fly above FL290 and RNAV capability will be a minimum requirement at and above FL180.
In this same time frame, operators desiring to fly into the nation’s largest airports will be required to comply with RNAV arrivals and departures. (Remember the transponder analogy?) At the end of the period considered under the plan—stretching out to 2025—FAA proposes mandating RNAV capability for all operations in the continental US and RNP in “busy” enroute and terminal airspace.
Avionics manufacturers offer significant PBN capability today, with the potential to grow with future requirements.
There is no doubt that NextGen/PBN/RNAV/RNP are here to stay and that advanced requirements are coming on strong. But there are numerous advantages to participating in the PBN world for all types of operator. Without question, efficiency and safety are significantly improved with the incorporation of PBN capable aircraft.
FAA’s documents espouse the virtues of RNAV and RNP, and their ability to maximize throughput both enroute and in the terminal environment. Fuel savings, improved traffic flow and reduced pilot/controller communications are just some of the advantages mentioned.
While many will be impressed with PBN’s ability to create curving approaches around steep terrain into airports surrounded by towering mountains, the real value in the majority of PBN applications will be the ability to “facilitate more efficient design of airspace and procedures.”