ATM Modernization, Business & GA, Commercial, Embedded Avionics

Routing RNP

By By James W. Ramsey | September 1, 2012
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Alaska Airlines, which pioneered RNP, has been flying RNP approaches into 27 airports. In 2011, these approaches saved the airline 210,000 gallon of fuel and $19 million.

Performance-based navigation (PBN), a key element in FAA’s NextGen air traffic control modernization initiative, is moving ahead, although at a somewhat slower pace than some airlines would like.

Satellite-based en-route and approach navigation is being used more extensively by airlines and business aircraft allowing aircraft to fly more directly to their destinations, saving time and alleviating airport congestion, while at the same time reducing fuel burn and emissions.

Although carriers are seeing some economic benefits from flying area navigation (RNAV) and required navigation performance (RNP) approaches and departures, some feel they are not being developed as quickly or utilized enough to make a business case for investing to equip their fleets and train their pilots.

“We’d certainly like to see some faster production than what we’ve got,” says David Newton, senior manager of NextGen and airspace for Southwest Airlines. Southwest has been the industry leader since it began RNP operations in January 2011 flying more than 5,800 approaches at 17 airports it serves with the majority of its Boeing 737 fleet equipped and all of its pilots trained for RNP.

Even though Southwest has flown more than 5,800 RNP approaches and departures since starting its program in January 2011, it amounts to only 1 percent of its total operations, Newton said. At the 17 airports it serves that have RNP approaches, they were used only 6 percent of the time. Pilots requesting RNP approaches often were not given clearance to use them, he adds.

Southwest is still evaluating whether RNP justifies its business plan of investing $90 million in cockpit equipment and pilot training, but in another areas it is paying off.

For its part, FAA maintains it is “on target” in developing these new procedures on the path to NextGen in 2020. “The whole point is to do everything we can to facilitate ADS-B (automatic dependent surveillance broadcast) on the path to NextGen in 2020,” the agency said. Clearing aircraft for approaches at airports that have RNP as well as standard ILS procedures is complex, FAA said. And while it would like to bring these benefits along faster, its main priority is always safety, the agency said.

To date, FAA has approved 305 RNP approaches, which require GPS navigation equipment on board the aircraft as well as FAA-approved pilot training, and plans call for 65 more RNP approaches to be approved this fiscal year. In addition, FAA has approved 297 RNAV routes, with 46 more planned.

“The whole effort is what can we do now with existing technologies that are on most aircraft to get some benefits we associate with NextGen. Let’s get started rather than waiting until 10 years from now hoping that all these things come available.”

“The whole effort is what can we do now with existing technologies that are on most aircraft to get some benefits we associate with NextGen. Let’s get started rather than waiting until 10 years from now hoping that all these things come available,” Newton said.

A recent FAA contract to ITT Exelis and GE Aviation could help accelerate the development of these satellite-based procedures. Under the $2.8 million contract, the two companies will develop two RNP approaches each into five airports at Dayton, Ohio; Kansas City, Mo.; Milwaukee, Wis.; Syracuse, N.Y.; and Anchorage, Alaska.

Except for several rare exceptions provided to GE Aviation, this is the first time private contractors will be allowed to design RNP approaches to be used by multiple carriers in the United States. (Previously, contractors such as GE Aviation were permitted by FAA only to design “special” RNPs for use by individual airlines.) The award emanated from the Systems Engineering 2020 program, which the FAA uses to select companies to work on parts of NextGen.

“The procedures must show benefits,” said Ken Shapero, director of GE Aviation’s PBN services group. “As part of the contract, we have to determine what the benefits are going to be and then we have to do a post-implementation analysis to verify that.”

GE Aviation, which has deployed and maintains 350 RNP procedures throughout the world, will handle the RNP design and procedure implementation, while prime contractor ITT Exelis is charged with program management and controls. The team will work closely with FAA to ensure safety and environmental processes.

The two-year program the first RNP approach is planned for Syracuse’s Hancock International Airport could lead to more third-party designed RNPs. “If it’s successful, there are an additional 50 airports out there that could be in line for some procedure work by us,” says Ed Sayadian, vice president of air traffic management for ITT Exelis.

RNP in Service

RNP, with its curved flight paths and more direct routing, can reduce the landing approach by about nine nautical miles, which reduces the landing time by three minutes and fuel consumption by 250 lbs., compared with conventional ground-based navigational approaches.

Alaska Airlines, which pioneered RNP flying into Juneau in 1996, has been flying RNP approaches into 27 airports, and in 2011 these approaches saved the airline 210,000 gallon of fuel and $19 million, according to Sarah Dalton, director of airspace and technology. She said there have been more than 1,500 occasions when RNP was used where aircraft would not have been able to get into or out of those airports.

“Pilots fly RNP approaches into southeast Alaska about 60 percent of the time, and another 25 to 30 percent of the time fly visual approaches. It has really become the preferred method for accessing those airports,” Dalton said.

RNP provides “a significant increase in the level of safety, because we are able to get both vertical and horizontal guidance into our runway ends, and using satellite navigation we have been able to cut our diversions and cancellations into these locations in half.”

Via its “Greener Skies over Seattle” program, Alaska Airlines, working with Boeing and FAA, in June flew satellite-guided passenger operations into Seattle-Tacoma International Airport.

“The objective (of Greener Skies over Seattle) is to reduce fuel burn and noise exposure for our operations here in Seattle,” Dalton said. The program began by flying two standard terminal arrival routes, with flight trials utilizing the FAA-designed RNP procedures due to begin in mid-July and continuing for six months with other airlines participating, including Horizon Air, US Airways and SkyWest.

Flying RNP procedures will shorten flight paths either 14 or 26 miles, depending on their approach route whether from the north or south. A turn over Elliott Bay rather than farther north will reduce jet noise from over-flights for 750,000 Seattle residents in northern neighborhoods, according to the airline.

Dalton says the flight trials will help FAA controllers refine and adapt their procedures at an airport using both standard ILS and RNP approaches. She says similar model programs are envisioned for Atlanta, and other locations.

Universal Avionics System’s UNS-1E flight management system has been used by Alaska’s partner Horizon Air to fly RNP approaches with its Q400s for five years. Universal said it has provided more than 2,500 of these space-based augmentation system (SBAS)-enabled flight management systems to the industry, most of them for corporate aircraft. (SBAS, which is used in Europe, is similar to wide area augmentation system (WAAS) in the United States.)

Universal’s newest system, the UNS-1EW, has been equipped on six of Horizon’s Q400s so far, and last fall, Horizon received special operational approval for RNP 0.3. This is the first such U.S. authorization obtained for an operator of turboprops, the company said.

Other Q400 operators including Air Canada and WestJet are moving towards WAAS and will have Universal’s 1EW system aboard, while Canadian North and First Air which operate 737s have Universal’s systems. Corporate aircraft with these systems include Cessna Citations, Lear Jets, Falcons, Gulfstreams and KingAirs, along with S-76, 212 and 412 helicopters. 

Graphic above depicts the Green Skies of Peru initiative. The GE-designed approach procedures saves an average of 19 track miles, 451 pounds of fuel and 1,420 pounds of CO2 emissions per flight between Lima and Cusco, the company said.

In a similar project, called “Green Skies of Peru,” LAN Airlines last February flew Latin America’s first continuously guided flight from takeoff to landing using PBN technology. LAN used the procedure on its Cusco-Lima route, using an RNP departure from the popular tourist destination, an RNAV airway en route, and an optimum profile descent (OPD) and an RNP approach into Lima’s Jorge Chavez International Airport.

In a collaborative effort between LAN, GE Aviation, CORPAC (Peru’s air navigation service provider) and regulator DGAC, the PBN procedure shortens the distance by 19 miles, saving 6.3 minutes, reducing fuel burn by 451 pounds (67.5 gallons) and cutting CO2 emissions by 1,420 lbs. per flight, according to GE and LAN. Since 2011, RNP approaches have been used by LAN to fly into three other cities in Peru, and it has been working to implement five RNP approaches at Lima.

In another overseas project, GE Aviation announced last May that PBN flight paths were validated at Jiuzhai Huanglong Airport in the Sichuan Province of China. GE says in this first public PBN project initiated by a Chinese airport, the paths will be available to all approved operators. Air China, China Eastern and Sichuan are expected to be the first three airlines to fly the procedures.

For Southwest Airlines, which announced in 2009 plans to spend at least $175 million to make its 500-aircraft fleet of Boeing 737s RNP-capable, has also conducted continuous satellite guided flight paths using optimum profile descents, says Newton.

“Cruising at 35,000 feet, OPD allows very defined windows on descent that allows us (the throttles) to be at near idle. And then can hook up with an RNP approach and have a continuous closed trajectory path from cruise all the way to the runway.

More than 370 of Southwest’s Boeing 737s are approved for RNP, and all new delivered aircraft, including its new 737-800s, are so equipped, while older non-equipped aircraft are being retired.

“At Southwest it is really about evolving our automation,” Newton says. He said a few years ago, pilots flew aircraft like they did in the 1980s. “Now we are using more modern displays and using more of the automation tools on the aircraft. The combination of (using) auto-throttles and VNAV is saving us over $1 million per month.”

With RNP procedures designed at 11 Southwest airports, the airline projects savings is $16 million a year, with an anticipated savings of more than $60 million per year once all Southwest airports have efficient RNP procedures.

In June, JetBlue Airways became the first FAA-certified carrier to fly a non-public RNP AR (approval required) approach into New York’s JFK International Airport using runways 13L and 13R with its A320s.

The new “special” RNP procedure will provide shorter flight times for customers, reduce noise levels and emissions and result in fuel savings up to 120 lbs. per flight, said Capt. Joe DeVito, manager of flight standards compliance. The airline began designing and testing these JFK special instrument procedures in 2004 in partnership with the FAA and MITRE Corp. All 2,300 of its pilots have been certified to fly RNP.

“What is unique about this approach is that it will allow JetBlue to utilize a decision altitude while in a slight turn to the runway, the first airline in the U.S. to harness this special capability,” DeVito says. The procedure allows for lower landing minimums, increasing runway utilization at JFK and reducing delays at JFK and other New York-area airports, he said.

Although curved approaches are common in RNPs, “in all the other procedures there is a lengthy straight segment after the final turn is completed. You don’t have that in this special procedure you are still in the turn when you reach the decision altitude.”

JetBlue uses Honeywell flight management system (FMS) on both the A320 and on the Embraer E190. (The airline has 122 A320s and 51 E190s.) DeVito said the airline was the first Airbus operator in the United States authorized for RNP AR, and the first to win authorization on the E190.

DeVito said he thinks FAA has been “more aggressive recently in putting these (RNP) procedures out there” and in contacting the carriers asking where they would like to see them implemented.

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