Threats, Noise Keys To Israeli Performance Based Navigation

Post by Alyce Shingler on December 15, 2016, updated on November 20, 2019

Aviation Week & Space Technology
John Croft
Thu, 2016­12­15 04:00

Israel is showing the aviation industry a new use for noise­ reducing and efficiency­ boosting performance­ based navigation (PBN) procedures: avoiding the rocket’s red glare. More to the point, the precisely defined narrow paths used in required navigation performance (RNP) approaches, a type of PBN procedure, could in theory allow the country to keep all runways at its main international airport, Ben Gurion, and others open during conflicts with its neighbors. The procedures, which are tied to avionics performance rather than ground ­based infrastructure, also could help with community relations by helping to curb runway activity in noise­ sensitive areas in the compact country, where the military controls most of the airspace.

From a military perspective, an advantage of RNP is it can precisely define routes that avoid major cities so the air force, if ever called upon, could use its Iron Dome interceptor system to destroy any incoming rockets and mortars without fear of striking a civilian aircraft.

“In times of conflict, RNP allows the aircraft to not be over major cities, areas Hezbollah and Hamas [would] very much like to target,” says Libby Bahat, head of the aerial infrastructure department for Israel’s Civil Aviation Authority (CAA), of the country’s enemies to the north and west, respectively. “Iron Dome allows the air force to defend those cities and yet allow normal traffic and normal civilian aviation to go into Ben Gurion [Airport].”

The CAA in November declared operational the country’s most precise PBN procedure to date: an RNP authorization required (RNPAR) approach designed by Houston based third party air navigation services provider Hughes Aerospace Corp. The RNPAR to Runway 30 at Ben Gurion, which is near Tel Aviv, a procedure that requires an airline to obtain special approval from regulators, replicates a straight in instrument landing system (ILS) approach with vertical and horizontal precision guidance, but adds the element of curves. Other PBN procedures in use at Ben Gurion are less precise.The Runway 30 RNPAR features “radius to fix” turns that guide an aircraft arriving from the west through a tear drop shaped pattern over the ground to remain clear of military airspace to the south and east of the airport.

The approach has vertical guidance and minimums of 280 ft. above the runway, twice as low as the previously available RNP approach to Runway 30. The RNPAR has other benefits. Chris Baur, president of Hughes Aerospace, says use of the approach, which took two years to develop in large part because of the complex airspace, also reduces track miles and saves fuel. He explains that the RNPAR’s radius to fix design offers better “containment” than legacy RNP procedures, an important element given the strong winds that typically blow eastward from the Mediterranean Sea. Baur says the CAA validated the approach with Hughes in a Boeing 737 simulator in Houston and later at Ben Gurion, using its Cessna Citation Mustang light jet.

Israel began deploying the PBN procedures in 2013 following a renaissance of sorts within the CAA, ignited by the FAA’s downgrade of the country’s safety ranking to Category 2 from Category 1 in 2008. “It was a very good move in the aviation history of Israel,” says Bahat of the changes spurred by the FAA action. Along with updating 80 year old aviation laws that apparently were in place under the British Mandate before the country’s founding in 1948, the CAA tripled its workforce to 120, adding “younger people from the industry that were still flying and knew the business very well.” The FAA restored Israel’s ranking to Category 1 in late 2012.

“One of the steps we did at an early stage was to explore PBN procedures,” notes Bahat, “not only for Ben Gurion, but for the entire route structure for the country.” The CAA published its first PBN procedure in 2013, and one new approach to a runway about every six months thereafter. In an unusual move, Ben Gurion asks aircraft to use Runway 30 and only with a PBN approach between of 11 p.m. and 1 a.m. “We received many requests to allow non PBN airlines to use the airport at that time, and we refused,” says Bahat.

The CAA already has published PBN procedures for its new Ramon International Airport near the southern city of Eilat, a facility ideally suited for the technology, as it is surrounded by mountains with large cities nearby. Ramon is scheduled to open in April 2017, and eventually is expected to have an ILS as well. “It will leave a lot of airspace free for Iron Dome and keep Ramon always open,” says Bahat.

Whether Ben Gurion or other airports will remain open to international airlines during times of strife is unclear. During the most recent conflict, in July 2014, the CAA kept Ben Gurion open, but the FAA banned U.S. aircraft from flying there for 36 hr. due to concerns over rockets and shelling. The European Aviation Safety Agency followed the FAA’s lead and also instituted a short term ban. According to Bahat, during conflicts, the airport has more operational freedom as its controllers can waive noise restrictions on some approaches.

There are no guarantees that RNPAR procedures will make a difference for U.S. carriers, which account for about one third of the traffic at the airport, if similar conflicts occur. However, Bahat says the CAA is “continuing cooperation with the FAA and the U.S. government in a very close, detailed way” and that the U.S. ambassador to Israel, Daniel Shapiro, has been to the airport several times during the past two years and appears to be knowledgeable about traffic flows and the Iron Dome. “He understands the very detailed operational risk analysis that we do and how we can have a very safe civilian aviation, and just a couple miles away have Iron Dome protecting a city. “If I have the FAA confident to keep [allowing] flying to Israel, I will have one big worry off my head,” he adds.

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