Upcoming developments could pave the way for helicopters to maneuver through even the most obstructive environmental obstacles.
Just in case you missed it, the future of navigation is here and ready to go to work. Once we understand what it can do for us. So before we can figure out where we are going, it makes sense to see where we’ve been and how we got there.
Legacy navigation, a term of endearment for how we navigated from place to place, was predicated on tracking and homing courses from ground-based radio stations. You went where it took you, not necessarily where you wanted to go. Hence the navigation was linear, not trajectory-based, and two dimensional, lacking a vertical path. This necessitated the “Dive & Drive” of descending on an instrument approach. Regretfully, this created the opportunity for controlled flight into terrain (CFIT), leading to catastrophic accidents involving aircraft large and small.
The legacy instrument flight rules (IFR) system was created for fixed-wing aircraft, and the helicopter pilot was further challenged by the inherent restrictions, inflexibilities and limited access IFR provides.
Before a durable system can be created to serve the vertical-flight community, the architects need to understand the limitations of helicopters and challenges encountered while operating in the legacy system. Arguably, the legacy system did not exploit the unique capabilities of the helicopter, being the only conveyance that can travel from point-to-point without the need for roadways, waterways or runways. My own experiences with copter IFR involved significant delays in obtaining an IFR release, wasting valuable fuel and ultimately receiving a clearance that would not resemble what was originally filed or required.
After finally taking off, and receiving vectors two states away, excitement built as the originally planned fuel margins evaporated, moving on to plan B. Ever present is the threat of icing – blade, structural and engine inlet. Clearly the legacy system assisted in creating the very risk and opportunities that IFR flight should avoid.
Further constraining copter IFR is the lack of a single-engine IFR certification program due to Part 27 requirements, which call for the same avionics certification standards for single-engine helicopters that are required for jets in the transport category.
According to industry advocates, among single-engine Part 27 helicopters worldwide from 2001 through 2013, there were:
Single-engine fixed-wing aircraft are not subjected to the same impediments as single-engine helicopters since they are required to follow Part 23 standards. This cultivates several questions. Why the difference? Is this requirement serving the industry or the flying public? Does it facilitate an acceptable level of safety? Do single-engine fixed-wing aircraft sustain unacceptable rates of failure on their components since they are not “protected” by Part 27?
In my experience, operating a single-engine turboprop almost exclusively single-pilot IFR, equipped with contemporary avionics, has demonstrated their robustness and reliability. Their capability has been equivalent to my experiences operating Part 25-certificated transport-category jets. If the requirements outstrip the benefits and the core issues are not being addressed, why continue down this path?
GPS changed all of that. At first, GPS was about the freedom to navigate directly between two points. This paved the way for instrument approaches with lateral guidance — standard instrument departure (SID) and standard terminal arrival route (STAR) — and vertical navigation.
Raw GPS has an accuracy of 10 meters. If the raw signal can be corrected for its local inaccuracies and position errors, the accuracy can be improved to 1 to 2 meters, and with the application of a flight analysis system (FAS) data block, vertical guidance.
Vertical guidance can also be achieved with barometric altimetry or GPS augmentation, known familiarly in the form of the FAA’s wide-area augmentation system (WAAS). There are two methods for delivering GPS augmentation: space-based augmentation (SBAS) and ground-based augmentation (GBAS). WAAS supports localizer performance (LP) and localizer performance with vertical (LPV) instrument approaches.
In the spectrum of helicopter IFR, hospitals and operators have a choice in selecting a service provider to develop, certify and maintain instrument flight procedures. Our goal at Hughes Aerospace has been to adapt the technology we’ve implemented in the air carrier community into the vertical-flight community, wherever it makes sense to do so. We have worked with the FAA over the past several years to examine the benefits of GPS and WAAS. To that end, we’ve been involved in serving the helicopter industry with instrument flight procedures (IFP), built by certificated and experienced terminal instrument procedures (TERPS) engineers, using industry-standard software tools and FAA public criteria.
Proponents are often confused between instrument procedures characterized as special or public procedures and the criteria that were used to develop the instrument procedures as proprietary or public. The vast majority of helicopter IFPs are characterized as special. Depending on your service provider, they can be developed and maintained to either proprietary or public criteria.
When IFPs are developed and maintained to public criteria, you can be assured that they are not restricted to a sole service provider and will be kept updated to the most current and relevant criteria.
Operators can also be confused as to what constitutes IFP maintenance. There are four elements of their maintenance:
As an FAA-authorized service provider, Hughes Aerospace possesses several letters of authorization, allowing it to perform heliport evaluations, IFP validation, as well as certification to develop and maintain IFPs. Hughes is one of two service providers that the FAA has authorized to develop and maintain Part 97 public instrument procedures as well as specials.
Helicopter IFPs typically consist of lateral navigation approaches (LNAV). They are depicted with a minimum descent altitude (MDA) and typically constructed with approach minimums around 450 to 600 feet and 1 square mile of visibility. Using WAAS, we can create instrument approaches with much lower minimums.
We recently developed the first helicopter localizer performance instrument approach, which has lower minimums than LNAV due to the superior accuracy (containment) of WAAS. Many contemporary avionics are capable of providing LNAV+V or LP+V instrument approaches. When you observe a +V, the avionics are providing LNAV with advisory vertical guidance (typically a 3-degree flight path angle, or FPA). This pseudo angle is extremely helpful in providing a stabilized approach, but bear in mind this is not based on a TERPS vertical surface. Oftentimes when you see an LNAV/LP+V procedure, it can be an indication of a possible obstruction that prevented the implementation of an approach with vertical guidance.
Localizer performance with vertical guidance, or LPV, is identical to a precision ILS instrument approach, featuring a DH or decision altitude with minimums as low as 250 feet and 3/4 square miles visibility. We can develop these instrument approaches with a variable geometric path or FPA beyond the fixed-wing standard of 3 degrees. Several contemporary autopilot systems will support FPAs of 7 degrees, allowing increased mitigation of terrain and obstacles.
En route connectivity is provided by helicopter routes, and until recently, helicopters were left using low-altitude “Victor Airways” or TK routes, which are extended transitions of instrument approaches. We have developed these routes independent of the approaches that can be line-selected in the flight management system (FMS). These routes are positioned to more favorably use airspace and mitigate terrain.
Another new element of navigation is the advent of the electronic flight bag (EFB). It supports a paperless cockpit, organizing charts, approach plates and manuals into a simple electronic repository. To better support EFB customers, we developed a digital, color-charting product that includes geo-referenced terrain contouring. Geo-referencing transforms the electronic chart, allowing the GPS feed from the EFB to provide own-ship display on the approach chart. This is a significant improvement in safety, providing the pilot with enhanced situational awareness while navigating the approach. Some EFBs that support automatic dependent surveillance-broadast (ADS-B) can provide weather and traffic overlays on a geo-referenced chart.
In the near future, required navigation performance based on WAAS will further enhance our opportunity to provide improved containment and utilization of airspace for helicopter navigation. This will provide routes and transitions closer to terrain and lower altitudes. Another element of this is the use of radius-to-fix (RF)-segment coding. The RF supports both precise lateral and vertical navigation, also allowing aircraft to safely maneuver around terrain and airspace constraints.
Today, we can go from a pile of dirt to a certificated heliport with advanced instrument procedures in less than a year, in support of safe, all-weather day/night operations.
“Again, it is a complex, tight airspace, with terrain and Iron Dome issues,” said Bahat. “RNP AR might solve many issues there. Due to issues that arose in previous conflicts, GLS [Ground-Based Landing System] might assist GPS jamming issues in LLBG, especially in times of conflict.”
Aviation Week & Space Technology
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.
Source URL: http://aviationweek.com/commercialaviation/threatsnoisekeysisraeliperformancebasednavigation
Aviation Daily August 2, 2016 p.4
WASHINGTON—A slate of donated required navigation performance (RNP) procedures for Tacloban City Airport (Daniel Z. Romualdez Airport) in the Philippines may set the stage for further improvements in the island nation’s ground-based aerial infrastructure.
The satellite-based procedures—one GPS approach, one required navigation performance (RNP) arrival and one RNP departure—were donated by Honeywell and partner company Hughes Aerospace, a provider of performance-based navigation procedures worldwide, in the wake of Typhoon Haiyan in late 2013. The storm knocked out the airport’s main terminal and its primary instrument approach aid, a very high frequency omnidirectional range (VOR) station. The RNP procedures are the first to be published in the Philippines.
The new GPS approach to Runway 36 offers a minimum descent altitude as low as 320 ft. compared to 745 ft. for the VOR approach. Aside from the lower minimum altitude, the satellite-based procedure also features fewer track miles and vertical descent guidance through the aircraft’s flight management system.
The RNP arrival procedure connects the non-radar en route environment to the Runway 36 approach, providing for a seamless, continuous descent to the runway. The design, featuring
multiple transition points along the circumference of a virtual circle around the airport, is specifically tailored to the local weather.
“The type of design lends itself well to an area with convective activity,” Chris Baur, president and CEO of Hughes Aerospace, said. “If you had weather that was shutting down one quadrant (of the circle), you can slide along the ring to pick up another transition to get to the airport.” Similarly, the RNP departure procedure seamlessly connects the airport to the en route environment for departures.
The new procedures were originally developed to be in place in advance of a papal visit in January 2015, however final approval by the Civil Aviation Authority of the Philippines (CAAP) did not occur until May 2016, with the three procedures going live in late June. Most likely users will include Philippine Airlines and Cebu Pacific, all of which must receive approval from the CAAP.
A Honeywell official based in the Philippines said in addition to a building an RNP approach to Runway 18 at Tacloban, the CAAC will also likely target “four or five” other airports that currently cannot receive airline traffic at night due to a lack of approaches and runway lights.
Cebu Pacific A320. Photo: Cebu Pacific Air.
In 2013, Typhoon Haiyan created a 13-foot storm surge in the Leyte Gulf that swept through the city of Tacloban killing more than 6,300 people and destroying nearly 1.1 million homes. After the storm, one of the only ways to get relief efforts to residents in the Tacloban region was through the Daniel Z. Romualdez Principal Airport. However, the airport itself also suffered major damage, as the storm destroyed its Very High Frequency (VHF) Omnidirectional Range (VOR) ground-stations and landing lights. That limited air relief operations at the time, but ultimately lead to a new satellite-based solution, the Philippines’ first Required Navigation Performance (RNP) 1 Standard Arrival Routes (STARs), Standard Instrument Departures (SIDs) and Global Navigation Satellite System (GNSS) approach into the airport. All of the new procedures were published in the International Civil Aviation Organization (ICAO) Aeronautical Information Publication (AIP) in June 2016.
“After the typhoon destroyed the VOR, we realized this was not the first time this happened and it was not going to be the last. In collaboration with Hughes Aerospace, we offered an immediate free-of-charge GNSS approach into the airport, so that when this happens in the future, the whole relief effort is not reliant on ground-based navigation aids,” Brian Davis, vice president of airlines, Asia Pacific at Honeywell Aerospace, told Avionics Magazine.
According to the International Federation of Red Cross and Red Crescent Societies 2015 World Disasters report, the Philippines is “one of the most disaster-prone countries in the world,” with more than 103 million people reportedly affected by natural disasters between 2005 and 2014.
The new satellite-based procedures help bring the Philippines into the next generation of commercial air transportation operations, as well. In December 2012, ICAO released a progress report on PBN implementation in the Philippines, showing the country’s first RNP approaches were implemented at two international airports, Ninoy Aquino International Airport (NAIA) and Puerto Princesa Airport, and one domestic airport, Iloilo Airport.
Other countries, especially western nations, are in the process of de-commissioning unused VOR stations. In the United States for example, the FAA released an official policy statement in July 2016 listing 308 VORs throughout the National Airspace System (NAS) that it is currently considering decommissioning.
While the CAAP ultimately ended up replacing its typhoon-destroyed VOR, Davis said all aircraft using the airport are equipped to fly the newly published PBN procedures, and airlines have welcomed them. Cebu Pacific, a low-cost carrier based in the Philippines, aided the effort to deploy the new satellite-based navigation procedures by allowing Hughes and Honeywell to use its AirbusA320 simulator to test the new procedures before they were made operational.
“We were able to lower the landing minimums over the traditional VOR approach. The new GNSS approaches were published in the AIP at the end of June, when the airlines flying there get their latest navigation database updates in their FMS, those approaches are there. We’ve received positive feedback from Philippines Airlines, and Cebu Pacific; they like the approaches because of the lower landing minimums, but they’re also using the existing [Standard Terminal Arrival Route procedures] STAR, which is now connected to the GNSS approach. So air traffic control already knows the airspace, the pilots already know the airspace, so not only was it a helpful on the landing minimums it was easy and useful to fly because they’re already used to that approach and direction into the airport,” Davis added.
The actual work between Honeywell, Hughes and CAAP to implement the new procedures began in 2014, Chris Baur, CEO of Hughes Aerospace, told Avionics Magazine. During the process of coding and flight-testing the new procedures, Hughes became the Philippines’ only licensed third-party Air Navigation Service Provider (ANSP), as it was required by CAAP to provide to provide the new procedures at the airport.
“These are the first RNP 1 procedures in the Philippines,” Baur said, noting that the new GNSS approach is a continuous descent approach that avoids flying to the VOR station and then outbound from the VOR.
“With PBN you can put the airplane where it needs to be. It reduces the amount of track miles flown, reduces the aircraft’s environmental impact, and fuel burn. It’s also continuous descent approach, versus the existing one where they had to fly to the VOR and then fly outbound from the VOR to make the final approach into the airport.”
Davis says the Honeywell-Hughes partnership, which has completed deployments for several other PBN projects in China, and Myanmar, among other regions, is currently in talks with Indonesia’s civil aviation authority to bring similar procedures to Indonesian airspace.
“Now that we have the first one to be published in the Philippines we’re going continue to expand PBN to the rest of the terrain-challenged areas of the Asia Pacific,” said Davis. “Right now, Indonesia has one of the highest rates of runway excursions. One of the things that we’re working on is promoting our Smart Landing Smart Runway capability, which is just a simple software upgrade to the Honeywell EPGWS computer, which is installed on 85 percent of the in-service fleet. So that is one of the technologies we’re working on for runway excursions, but the other key initiative is to usher in more PBN approaches throughout the region.”
With the first operations utilizing performance-based navigation taking place in Europe, we take a look at how the concept may offer significant potential to improve reliability and safety in the helicopter industry.
By Mario Pierobon
As part of the PBN concept there exist two main macro-categories of navigation specifications: area navigation (RNAV) and required navigation performance (RNP). The main difference between RNAV and RNP is the requirement for on-board performance monitoring and alerting. A navigation specification that includes a requirement for on-board navigation performance monitoring and alerting is referred to as an RNP specification. One not having such a requirement is referred to as an RNAV specification.. The capability to undertake performance-based navigation (PBN) for both rotorcraft and fixed-wing aircraft is one of the “future” navigation concepts being embraced by industry experts around the globe in the present. Representing a shift from sensor-based navigation, the PBN concept sees performance requirements identified in navigation specifications, which also identify a choice of navigation sensors and equipment to be used to meet the performance requirements.
According to the International Civil Aviation Organization’s (ICAO’s) PBN manual (Document 9613), the PBN concept specifies that aircraft RNAV and RNP system performance requirements must be defined in terms of their accuracy, integrity, continuity and functionality.
Under PBN, generic navigation requirements are defined based on operational requirements. Operators then evaluate options in respect of available technology and navigation services, which could allow the requirements to be met. An operator thereby has the opportunity to select a more cost-effective option, rather than a solution being imposed as part of the operational requirements. Technology can evolve over time without requiring the operation itself to be reviewed, as long as the expected performance is provided by the RNAV or RNP system, according to ICAO.“The PBN concept suggests that RNAV specifications are effectively legacy specifications and that no new RNAV specifications will be developed,” states a PBN briefing paper from the European Organisation for the Safety of Air Navigation (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.”
FORGING A PATH
In Europe, some of the first applications of PBN have already taken place using the Localizer Performance with Vertical Guidance (LPV) approach and RNP 0.3, which are both part of the PBN family of navigation specifications.
In June 2015, a CHC Helikopter Service Sikorsky S-92 equipped with dual Universal Avionics SBAS-Flight Management Systems (FMS) car- ried out the first LPV approach to Florø, one of the first Norwegian air- ports to be equipped with LPV capability.
In Switzerland, Rega, one of the country’s leading helicopter emergency medical service (HEMS) providers, has been working closely with the Swiss Air Force on a RNP 0.3 low flight network (LFN) that links hospitals as well as military airfields and landing sites. The Norwegian Air Ambulance is involved in a similar project to achieve an RNP 0.3 instrument flight rules (IFR) route net in Norway.
RNP 0.3 is a navigation specification for all phases of helicopter operations with a requirement for on-board navigation performance monitoring and alerting. Under this navigation specification, the required accuracy is 0.3 nautical miles (nm) for all phases of flight, which means that during operations in airspace or on air traffic service (ATS) routes designated as RNP 0.3, the lateral total system error must be within ±0.3 nm for at least 95 percent of the total flight time. The along-track error must also be within ±0.3 nm for at least 95 percent of the total flight time. To meet this performance requirement, a flight technical error of 0.25 nm (95 percent) may be assumed.
With regard to the navigation needs of helicopter operations, ICAO’s PBN manual highlights that: “The helicopter community identified a need for a specification that has a single accuracy of 0.3 nm for all phases of flight, recognizing that such a specification would enable a significant part of the IFR helicopter fleet to obtain benefit from PBN.”
According to ICAO, the operations envisaged by the helicopter community included reduced protected areas, potentially enabling separation from fixed-wing traffic to allow simultaneous non-interfering operations in dense terminal airspace, as well as low level routes in obstacle- rich environments to reduce exposure to icing environments. Seamless transition from en route to terminal route was also envisaged, as well as a need for more efficient terminal routing in obstacle-rich or noise-sensitive terminal environments — something particularly relevant to HEMS IFR operations between hospitals, and around airports supporting the offshore industry. Other operational needs leading to the development of the RNP 0.3 navigation specification included transitions to point in space (PinS) approaches and for departures.
“Most modern IFR twins now come suitably equipped [for PBN] as standard,” Steve O’Collard, a technical pilot at CHC Helicopter, told Vertical. “In addition, there are after-market systems that are fully compatible.” According to Robert Clare, Universal Avionics’ director of sales, there are approximately 120 S-92s in the field with his company’s SBAS- FMS system installed.
Indeed, significant benefits are enabled by LPV approach procedures in that they allow approaches using on board global positioning system (GPS) rather than ground-based systems such as the instrument landing system (ILS). “LPV permits approaches to lower minima in cases where the local ground-based systems may not [such as VOR or NDB, which do not permit the same degree of accuracy], or where there are no ground-based systems, with potentially significant operational benefits,” said O’Collard. “The flight path is not affected by terrain interference; indeed ground-based signals can be ‘bent’ by terrain or by interference from, for example, other aircraft.”
With regard to PBN aeroplane operations, terminal and en-route navigation requires less navigation accuracy (RNP 1 and RNP 2, respectively). “ICAO PANS-OPS now allows RNP 0.3 operations for helicopters ‘in all phases of flight,’ ” said Lukas Kistler, lead pilot of Rega’s EC145 fleet. “This enables more flexible helicopter-dedicated en route IFR segments in difficult terrain with many restricting obstacles. By minimizing the size of the obstacle-free corridor, the routes can be designed at lower altitudes where generally warmer temperatures prevail. This in turn allows non de-iced helicopters to operate IFR on days where higher airways are already in an icing zone.”
In Europe, there are not many large-scale implementations of PBN for helicopter operations beyond the use of LPV approaches to aerodromes that have published RNP approach procedures to LPV minima. The acceptable means of compliance to the PBN section of European Aviation Safety Agency (EASA) air operations regulations dealing with operations that require specific approval aren’t even published for the RNP 0.3 specification. This means that operators wanting to implement RNP 0.3 — to derive the benefits of PBN for phases of flight other than the approach phase — must refer to ICAO’s PBN manual.
Kistler said that bad weather currently prevents around 600 people from receiving emergency assistance from the air each year in Switzerland. “We see the possibility to increase the number of patients we are able to transport in marginal weather conditions [through the LFN],” he said. “We also believe that by routinely flying on an established, well known IFR network, we can further improve the level of safety as opposed to NVIS-aided VFR [visual flight rules] night operations.” According to Kistler, another setting where RNP 0.3 helicopter operations could provide benefit to both helicopter operators and wider air navigation systems are IFR transit routes through busy airspace at inter- national airports.
Over in the U.S., Hughes Aerospace Corporation, based in the Woodlands, Texas, is one of just two companies both endorsed by ICAO and certified by the Federal Aviation Administration (FAA) to develop, validate, and maintain FAA public (part 97) IFR procedures, as well as special IFR procedures for helicopter and fixed-wing operators worldwide. Hughes implemented the first public RNP approach procedures at Chicago O’Hare International Airport, which the company still maintains on behalf of the FAA. “We also develop and maintain helicopter PBN procedures,” Chris Baur, president and chief executive officer of Hughes Aerospace, told Vertical. “In the U.S., there are no IFR heliports, hence [helicopter] IFR procedures are categorized as special instrument procedures, developed as “PinS” or ‘Point in Space’ procedures. . . . There are [also] hundreds of special LNAV instrument approaches and departures, along with more contemporary LPV procedures.”
The company has worked with the FAA to prototype the use of the Wide Area Augmentation System (WAAS) and the use of “RF” (radius-to-fix) segment coding for
helicopters, leveraging the accuracy level and superior containment of WAAS and advanced ARINC 424 binary code. Baur noted that the FAA does not characterize helicopter RNP instrument approaches as RNP 0.3 naviga- tion, but it recently published criteria for RNP
0.3 IFR low level routes, supported by WAAS. Raw GPS has an accuracy of 10 meters, but if augmented by either space-based or ground- based augmentation systems, it can achieve accuracy levels of one meter and 10 centime- ters, respectively.
“In order to execute an RNP approach, you need to have special equipment and aircrew training,” said Baur. “The equipage requirements include dual flight management computers [FMC] and inertial reference systems [IRS]. In the event of a catastrophic reception failure of GPS updating to the FMC, the IRSs are used to perform an extraction maneuverer [missed approach], providing sufficient contain- ment until the aircraft is positioned at a safe altitude. Helicopters do not normally have a dual inertial reference system — the project we did with the FAA was to see illustrate how operators could use the containment accuracy of WAAS (SBAS) demonstrated at 0.3 RNP to alleviate the need to have [one].”
TECHNICAL AND OPERATIONAL REQUIREMENTS
For a helicopter company to perform PBN operations, O’Collard said it must first install equipment that satisfies the “aircraft requirements” of navigation specifications. Next, it must have operational approval from the applicable civil aviation authority to use the equipment. “This approval will cover not only normal and abnormal operational procedures, but also training,” he said.
ICAO’s PBN manual highlights that airworthiness certification and recognition of RNP 0.3 aircraft qualification alone does not authorize RNP 0.3 operations. “Operational approval is also required to confirm the adequacy of the operator’s normal and contingency procedures for the particular equipment installation applied to RNP 0.3 operations,” the manual states.
According to ICAO, the operating procedures to be developed, docu- mented and implemented include pre-flight planning, RNP 0.3 availability prediction, general operating procedures, RNP 0.3 standard instrument departure (SID) and standard instrument arrival route (STAR) specific requirements, as well as contingency procedures in case of loss of the RNP 0.3 capability.
The training program should provide sufficient training (in a simulator, training device, or aircraft) on the aircraft RNP system to the extent that the pilot is familiar with the content of the RNP 0.3 navigation specification in ICAO’s PBN manual. Flight crew training should also include required navigation equipment and minimum equipment list for operation on RNP 0.3 ATS routes and RNP system-specific information. Simulator and/or aircraft training should also be delivered to familiarize the flight crews with RNP equipment operating procedures and as contingency procedures.
To make it possible for the air navigation system to enable the high standards of PBN operations, a very peculiar system component comes into play: the variety of satellite based augmentation systems (SBASs) that operate in different regions of the world. While the GPS has been used successfully in aviation for many years, Universal Avionics said the basic technology does not produce adequate precision and accuracy to allow it to be used as a sole source of navigation. “The accuracy and integrity of GPS is greatly enhanced by the use of augmentation information from a variety of sources,” states a Universal Avionics’ document on SBAS. “[SBAS] augments the GPS signal to produce an increased accuracy, integrity, reliability and availability of information for aviation. With the decommissioning of legacy ground-based navigation systems, regional SBAS programs have grown substantially over the past five years. This technology is a critical component of the FAA’s Next Generation [NextGen] program and the Eurocontrol SESAR [Single European Sky ATM Research] initiative.”
An SBAS consists of a network of precisely surveyed ground reference stations strategically positioned to monitor, collect and process satellite signals. The ground reference stations send satellite signal data to ground master stations, which then take measurements of signal delay and other errors (such as ionospheric and/or solar activity) that may impact the signal. Using the signal error measurements, master sta- tions develop corrections to the information obtained from the ground reference stations and send a corrected, or augmented, message to Geostationary Earth Orbit (GEO) communication satellites. These GEOs then broadcast the message to the internal SBAS receiver in an SBAS- capable FMS. Paul Damschen, Universal Avionics’ manager of airworthiness and flight operations, said the LPV approach does not require RNP 0.3 — in fact, it requires a much lower RNP value. “LPV approaches require a horizontal and vertical alarm limit of 50 meters, so positional accuracy to support those operations is much lower than basic RNP 0.3,” he said. “Basic RNP 0.3 does not require SBAS augmentation, and TSO C129 as well as TSO C146 equipment can support RNP 0.3 for en route, terminal, and approach. LNAV-only approach can be conducted under RNP 0.3, again, without SBAS augmentation.”
Several regional SBAS programs have been implemented so far, each complying with a common global standard. Therefore, all are compatible and interoperable, and do not interfere with each other. An operator with an SBAS-capable receiver can benefit from the same level of service and performance no matter which coverage area they are in. Existing and in-work SBAS include the WAAS in North America; the European Geostationary Navigation Overlay Service (EGNOS) in Europe and North Africa; the Multi-functional Satellite Augmentation System (MSAS) in Japan and GPS-Aided Geo-Augmentation Navigation (GAGAN) in the Indian subcontinent.
To achieve the high level of safety that RNP operations provide, espe- cially in terminal areas where approaches without a vertical glide path will be history, the airspace providers and the operators have a signifi- cant responsibility ahead of them. “While GSA in Europe is finalizing the SBAS coverage to achieve lowest LPV minima at all airports, the national airspace providers at airports should be designing new RNP approaches to replace existing conventional approaches,” said Jørgen
Staffeldt, a type technical pilot of the S-92 at CHC Helicopter. “In parallel, the operators should be updating aircraft to SBAS capability and training the crew to achieve RNP authorization.
“On the other side, the helicopter OEMs should be working on the certification of aircraft to not just SBAS capability, but future NAV SPEC capability, including today’s RNP AR [Authorization Required] that cur- rently include Radius-to-Fix legs to be used in approach procedures, to achieve shortened and more flexible approaches,” Staffeldt continued. Baur noted that the several hundred public LPV procedures existing in the world are published for fixed-wing operations, while the majority of helicopter LPV procedures are special instrument approach procedures. “[Helicopter] instrument procedures in the United States are developed by third party service providers, such as Hughes Aerospace,” he said. “The FAA has issued Hughes with the authority to perform heliport evaluations, flight, simulator and obstacle evaluations as well as proce- dure maintenance.”
Baur notes that one of his company’s recent achievements has been to publish the first LP [Localizer Performance] helicopter approach procedure in the United States. “This type of approach provides sig- nificant benefit to the operator, in a situation where you are not able to provide the vertical guidance because the aircraft is WAAS [or SBAS] equipped but does not have the necessary equipage for LPV,” he said. “LP approaches provide lower minima than non-augmented LNAV approaches. The WAAS constellation supports a tighter accuracyand containment, with the potential to eliminate obstacles and reduce minima required with LNAV.”
PBN for rotary wing operations has significant potential to improve reliability and safety as well as air traffic management. However, it still has to develop a critical mass. While the availability of technology installations and upgrades put PBN within easy reach for operators, without the sup- port of air navigation service providers (who must develop more public PBN procedures) and industry regulators (who must oversee the opera- tors wanting to upgrade to PBN capability), the benefit of PBN operations for the helicopter community will remain largely unfulfilled.
www.verticalmag.com June/July 2016
Tuesday, April 12, 2016
United Flies First RNP Procedures in Micronesia
“I’ve been flying since 1979 and I’m blown away by how far we have come. The FAA deserves a lot of credit because they incubated, a lot of this. We have worked with them on it over the years; they are the ones who put this whole plan together. While I think they catch a lot of heat about NextGen, at least from our perspective we think they are doing a great job with NextGen and we enjoy the opportunity to work with them on the implementation of things like this,” he added.
Aviation Week & Space Technology
Feb 19, 2016
A new breed of procedure designers is mapping fast lanes above and beyond.
Building highways in the sky requires getting your feet dirty. Luckily, I wore boots the day I accompanied a team from Hughes Aerospace Corp. through the ranchlands of Cisco, a tiny rural town smack dab in the middle of Texas. Today’s job: validating a slate of new performance-based navigation (PBN) procedures that Hughes built for the operators of a new airport in Cisco. At the edge of the Angle R property, adjacent to an approach path, a tree limited the minimum altitude for a certain approach; its height had to be verified for a final data package to be sent to the FAA for approval of the procedures.
What is unusual at Gregory Simmons Memorial Airport is that the owners, with a small fleet of Cessna and Bombardier business jets, did not look to install any land-based instrument approaches: They jumped right into the future. That future will largely consist of approaches and departures defined by global navigation satellite systems (GNSS), GNSS augmentation systems, GNSS-based landing systems, or required navigation performance (RNP) avionics—rather than procedures linked to traditional land-based systems such as VORs or instrument landing systems. Along with lower costs—no ground infrastructure has to be purchased and maintained—PBN is more efficient, allowing for more direct routes, safe passage around obstacles and an associated reduction in fuel burned and carbon emissions. Continue reading
Aviation Today :: Global PBN Deployment Arrives in Middle East
“This is a start; there is always a starting point and I think now we have changed the mentality of so many people here with the procedure, especially the authority. They saw it can be done and we are getting more confident. I believe there is room for another one here, and perhaps other areas throughout the region as well,” said Jaramillo.