With demonstrated benefits of reducing track miles, mitigating noise and lowering fuel burn and emissions, performance-based navigation (PBN) procedures are being adopted on a worldwide basis. But 15 years after Alaska Airlines flew the first procedures, widespread implementation of PBN is uneven and its benefits largely unrealized.
“There’s no doubt PBN is the right thing to do, and yet we’re not seeing the sort of progress we’d like. What is it about PBN that is so hard?” asked Graham Lake, director general of the Netherlands-based Civil Air Navigation Services Organization (Canso). “We know that it is safe and enables precision approaches into places where precision approaches are not available; [that it] encourages application of stable approaches, enables separation in the ATC environment and continuous departure time in dense air traffic environments, yet it’s not being deployed.”
Lake was among speakers from Europe, North and South America, Australia and New Zealand who reported on progress toward deploying precision navigation procedures at the fifth annual PBN Summit, sponsored by GE Aviation in Seattle in late September. A theme that emerged was that application of PBN, and specifically satellite-guided required navigation performance (RNP) procedures, while well established in some places and among some operators is being slowed by environmental challenges in designing flight routes, mixed fleets with older aircraft that are incapable of RNP, as well as lack of trained air traffic controllers to manage aircraft that are capable.
Steve Fulton, technical fellow with GE Aviation PBN Services, opened the two-day conference by highlighting progress toward International Civil Aviation Organization (ICAO) resolution A36-23, which calls on member states to implement approach procedures with vertical guidance (APV) as a primary or back-up approach for all instrument runway ends by 2016.
The 2007 resolution was superseded in October 2010 by A37-11, which implores states to complete PBN implementation plans “as a matter of urgency,” and adds straight-in lateral navigation (Lnav) only procedures as an exception for aircraft without vertical navigation capability, or for airports without local altimeter settings. The first milestone was to achieve 30-percent global deployment of PBN procedures by 2010. One year later, the deployment rate is 15 percent.
Fulton, who helped develop the first RNP approaches into Juneau and southeast Alaska in the 1990s as a technical pilot with Alaska Airlines, used a graphic based on ICAO data showing the greatest concentration of APV approaches including Lnav-only procedures in North America, with 21 percent to 50 percent of instrument runways enabled. Central and South America are second, with 11- to 20-percent deployment. Europe, Asia, the Middle East and Africa have 0- to10-percent deployment.
Ground Tech Lags Air
Developments on the ground lag technology in the air. Globally, 57 percent of airliners are capable of performing RNP operations, according to information presented at the summit. By region, the Middle East leads with 80 percent RNP-capable aircraft in service or on order, followed by Asia (71 percent), Europe (64 percent), Latin America and the Caribbean (50 percent), Australasia (49 percent), North America (43 percent) and Africa (39 percent). Nearly all aircraft on order are RNP capable.
Franca Pavlicevic, head of the Eurocontrol navigation research unit, said Europe is “very much moving from” area navigation (Rnav), allowing for a choice of flight paths within coverage of ground navaids, or using global navigation satellite system (GNSS)-based position, to RNP, which differs in requiring onboard performance monitoring and alerting for positional assurance.
The expectation is that RNP approach (APCH) procedures, requiring lateral accuracy of 0.3 nm in the final approach segment, will be achieved in 2018. Vertical guidance will be enabled either by barometric altitude calculation or satellite-based augmentation system (SBAS). “We are looking to really push APV approaches and vertical guidance. Whether we do it using SBAS or baro, we don’t really care, just as long as we can get vertical guidance,” Pavlicevic said.
Moving from basic Rnav procedures implemented in 1998 to RNP APCH effectively will be a 20-year process, slowed by mixed fleets of RNP-capable and older, less capable aircraft, Pavlicevic said. “We’ve got 1970s [flight management systems] still flying in the airspace. Thirty-five percent of the [IFR] fleet does not have GPS,” she said. “We envy you who have an aircraft fleet with an average age of eight years. …We have the best in class, who want to use all the [equipment] they have, and those with older aircraft, who are saying we really don’t want to spend the money because it costs too much.”
Nevertheless, the European Comission has directed Eurocontrol to draft a PBN implementing rule that will define navigation requirements in enroute and terminal airspace, a rule that would have to be approved by the 27 European Union member states. “We have a scenario on the table, but it’s always the battle between the air and the ground,” Pavlicevic said. “Who do we make pay the bill? Do we get the aircraft to equip? Then [airlines] complain quite rightly they’re carrying the cost while [air navigation service providers] don’t have to carry any cost.”
Alternatively, Europe could opt for a phased implementation of PBN, allowing operators to equip “naturally,” as aircraft are replaced–an idea popular with airlines. “The problem is that managing the mixed mode [fleet] is extremely difficult,” she said.
Meanwhile, in South America
PBN is progressing in other parts of the world. Chile’s LAN Airlines is flying RNP procedures with Airbus A320s at five airports in Chile and Peru and plans four more airports by year-end, said Capt. Christian Staiger, LAN technical pilot. Seventy-five percent of its flight crews are certified to fly the precision approaches.
The Santiago-based carrier, which plans to merge with Brazil’s TAM Airlines to create the largest airline in Latin America, is working with GE Aviation to implement RNP procedures at Lima’s Jorge Chavez International Airport. Staiger said Lima is expected to be the first airport where RNP operations are performed by the Boeing 787 Dreamliner, which LAN will begin receiving in 2012.
Australia’s Qantas celebrated its eighth year of strict RNP Authorization Required (AR) operations in September using Boeing 737-800s. The carrier is flying RNP procedures at 16 airports in Australia and has logged more than 170,000 RNP AR operations, said Paul Taylor, senior air safety auditor with the Australian Civil Aviation Safety Authority (Casa). The airline next will begin RNP operations with its Boeing 767s. Air New Zealand operates A320s on RNP routes into Brisbane and Gold Coast, Australia.
Taylor said Casa is collecting operational data from aircraft quick-access recorders after each RNP AR flight by Air New Zealand, Qantas and Qantas low-cost subsidiary Jetstar Airways to support the case for reduced aircraft separation standards. The agency also is collecting automatic dependent surveillance-broadcast tracking data from Airservices Australia. “We’re using statistics to make a safety argument for reduced separations,” Taylor said.