DESIGNING THE APPROACH CUSTOMIZED INSTRUMENT PROCEDURES

Post by Alyce Shingler on October 20, 2019, updated on May 14, 2020

You are cleared for the RNAV RWY 19R approach at Dulles (KIAD) flying the LPV. At LAUGH waypoint, you are at 3,000 MSL and start your descent on the glide path. The METAR shows a ceiling of 300 AGL, just above minimums. You break out of the clouds just before the DA of 478 and land. As pilots, we know of the work it takes for ATC to help us land safely, but are mostly unaware of what it takes to create the instrument procedures themselves. The United States alone has 12,000 instrument approaches, 7,200 of them based upon GPS. Each one goes through a detailed design, test, implementation and maintenance process.

GPS-based approaches are increasing at a rapid rate due to the lower cost and relative ease of design and certification in comparison with VOR or localizer-based approaches. Even with a large number of approaches available, we can always use more, especially at smaller airports, heliports and private landing facilities. As capabilities of satellite-based navigation increase, so do the possibilities for pilots. One of the newest options are curved Radius-to-Fix (RF) approaches, with each leg defined by a radius, arc length and fix. These approaches offer pilots the capability to maintain very precise tracking along curved paths when using approved GPS navigation systems. The first such approach was established at the Ronald Regan Washington Airport (KDCA) in 2003. Another example is the RNAV (RNP) RWY 31 at Palm Springs (KPSP). In order to utilize these approaches, both aircraft and aircrew must be authorized.

The complicated designs are created by the FAA and other government agencies worldwide, along with a small group of private companies. Hughes Aerospace, based in Houston, falls into the latter group. Hughes possesses certifications from the FAA as a Public Part 97 Air Navigation Service Provider, certificated to design, implement and maintain a wide variety of Instrument Flight Procedures (IFR) – particularly satellite-based navigation such as LPV approaches, RNAV SIDs and STARs. Additionally, Hughes Aerospace is certificated by ICAO and several other government regulators worldwide. Hughes not only designs instrument procedures for public airports but they develop and maintain them for private airports and heliports as well.

I reached out to Chris Baur, president and CEO of Hughes Aerospace, to discuss instrument procedure design. Chris, an experienced pilot with both fixed-wing and rotorcraft flight time in the military and civilian arenas, has been designing instrument procedures for more than 10 years around the world.

Chris Baur with Hughes Aerospace was instrumental in the design of a public complex RF approach at Pohnpei International (PTPN) in the Federated States of Micronesia that includes radial-to-fix segments on both the final and missed approach portions of the RNP RWY 9 procedure.

Approaches for Private Airports and Heliports

For private landing facilities such as residential airparks or medical heliports, an instrument procedure dramatically increases the utility and safety. In many cases, a satellite-based procedure is the only solution, especially in environments where terrain and obstacles prevent the development of other approaches. Performance-Based Navigation (PBN) procedures can be designed with either linear or non-linear (also called trajectory-based) flight paths that can provide lower minimums.

With increasing population density surrounding airports and heliports, custom procedures can also help mitigate the noise impact on the surrounding community. Hughes Aerospace has worked on a number of these solutions over the last 10 years.

The design and implementation processes are complex, starting with remote site analysis, which uses a variety of data sources from topographical and aerial surveys to local planning documents. All procedure designs then require a detailed on-site survey. After the initial design, and coordination with the FAA and other agencies, the procedures must then be test flown. Hughes Aerospace uses their own Piper Meridian and Robinson R66 as the test platforms, flying the approaches to verify they meet requirements. Once the testing is complete and the procedure approved, Hughes coordinates the publication of the data in the databases, and in the case of private operators, the issuance of the full-color geo-referenced procedure.

In order for the procedures to be active, they must be monitored daily, including managing the NOTAM service for any changes or variation in service levels. For the majority of approaches that are managed by the FAA, it is their responsibility. For those custom designed for private operators, Hughes Aerospace provides these services.

A 3-D map from a site inspection in Calexico, California.
Image Courtesy of Hughes Aerospace

Behind the Scenes Look

I recently accompanied Chris on a site inspection for a heliport in Calexico, California – only a few miles from the airport (KCXL) and a stone’s throw from the United States/Mexico border. Chris and his team already completed initial design work remotely, and the mission this visit was to confirm obstacles and obtain the most accurate data on the helipad and surrounding area.

We flew from Montgomery Field (KMYF) to Calexico in my Eclipse 500 for the site evaluation. The initial ground survey included mapping the obstructions in the local area with high precision, including their latitude and longitude as well as height. Next was the inspection of the landing site itself. Chris made precise measurements of the helipad, then proceeded to use a small UAV to map the location in detail.

I previously owned a photogrammetry company and it was fascinating to see Chris utilize the latest generation of high-resolution technology. The UAV was the perfect aerial platform for this work, flying a precise pattern to assist Chris and his team with creating an accurate 3-D map of the heliport and surrounding areas. This data can then be combined with their other sources to develop the precise paths for the instrument procedures. Each site offers new challenges. This one, in particular, had the Mexico border, large communications towers, as well as buildings near the helipad.

Hughes Aerospace will take this data to design the instrument approach and departure procedures for their customer. And the work won’t stop after the FAA approval since they must monitor and maintain the procedures for as long as they are active.

The next time you are briefing for your instrument approach, or reviewing a departure or arrival procedure, remember that aviation professionals created each one of those altitudes, headings, speeds and notes with an attention to detail – and one focus – safety.

BY RICH PICKETT
SEPTEMBER 26, 2019
FEATURE
http://twinandturbine.com/article/designing-approach-customized-instrument-procedures/

Airliner Style PBN for Helicopters

Post by Alyce Shingler on March 4, 2019, updated on November 21, 2019

Avionics International had the opportunity to sit co-pilot during a demonstration of the world’s first-ever helicopter radius to fix procedures.

WOODROW BELLAMY III

http://interactive.aviationtoday.com/avionicsmagazine/february-2019/airliner-style-pbn-for-helicopters/

A collaborative use of instrument flight rules procedures and new flight control systems from Hughes Aerospace, working with the FAA, Garmin and AeroNavData, has produced the world’s first use of radius to fix segment coding for helicopter instrument approach and depart procedures.

In December 2018, Hughes Aerospace CEO Chris Baur completed a flight validation of new helicopter IFR procedures using RF for a route consisting of eight different heliports between Morgantown, West Virginia, and Baltimore, Maryland. Baur and the air navigation service provider design team from Hughes developed the low-level helicopter procedure network, culminating during a week-long flight validation activity in the Hughes R66 flight inspection helicopter.

The new procedures use the latest FAA criteria featuring Required Navigation Performance (RNP) 0.3 and RF segment coding. RNP is a performance-based navigation concept using internationally accepted specifications that create precise and determined pathways for fixed and rotary-wing aircraft.

RNP 0.3 is the requirement for an aircraft’s navigation system to be capable of calculating its airborne position within a three-tenths of a nautical mile, and it is the International Civil Aviation Organization’s acceptable level of accuracy for the use of RNP in all phases of helicopter flight. Operators seeking to use RNP 0.3 today are required to add helicopter RNP H124 to their operations specification.

Baur provided an in-the-cockpit flight procedure validation to Avionics International demonstrating the use of RF approaches at one of the hospitals along the new route – Garrett County Memorial Hospital. His company is using a Garmin-equipped Robinson R66 featuring high resolution twin glass displays, and a digital autopilot with stability augmentation and ADB-B In and Out.

One of the central components enabling the new RF approaches is the 66’s Garmin GTN 650H flight management computer. The FMS featured a special navigation database reserved for flight inspection.

“This is historic,” Baur said, as he removed his hands from the controls and watched the GTN 650 autonomously control the R66 from waypoint to waypoint.

It’s the type of flying that Baur, a 40-year veteran helicopter pilot and airline captain, said is common in the commercial airline world but still limited to small pockets of the vertical flight community.

“We want to deliver these type of advanced helicopter Instrument navigation procedures, now common in the air carrier community, to our customers in the vertical flight community,” he said.

“The confluence of RF turns and LPV are used to mitigate heliport obstacles, terrain, noise and airspace issues, while providing safer, lower instrument approach minimums. It’s also wind independent, we noted the wind direction and velocity on each RF leg and recorded bank angles as well. The highest bank angle at any time within this approach was nine degrees. Typically in any helicopter PBN procedure design you want to use less than 20 degrees of bank angle,” he said.

The effectiveness of the RF leg was shown during the first flight demonstration Baur performed in December, which featured cross and tail winds ranging from 20-30 knots. Even in those conditions, the helicopter was able to perform with a cross track error of just 0.00-0.01, or remain within 60.7612 feet.

The procedure was created featuring helicopter RNP 0.3 and radius-to-fix segment coding as a demonstration procedure designed for use by the Maryland State Police.

Baur’s experience flying commercial airliners showed him that through experience the use of RF legs in en route airspace has little-to-no benefit for fixed wing operations. However, at lower altitudes, where helicopters need to fly within defined paths and avoid encroaching on nearby airspace when approaching heliports with terrain and environment obstacles, it can help the helicopter fly the approach more efficiently, especially in IFR conditions.

He sees the use of RF legs in PBN procedures holding massive benefits for reducing fuel and the number of track miles flown, as well as decreasing communication between pilots and controllers attempting to complete point in space helicopter landings.

As the PBN movement spreads into helicopters and the vertical flight community, the benefits in safety, accessibilities and efficiencies are clear, as operators leverage their investments in avionics, particularly in the United States and Europe. This is an example of industry and government collaboration, that has delivered success.

“In these cases, Hughes Aerospace develops a custom procedure, such as the one landing on the helipad at Garrett County Memorial Hospital, and provides this electronically to Garmin,” Bill Stone, senior manager of business development for Garmin’s aviation division said, describing the process of getting the new procedure into the Hughes R66 for flight testing and procedural validation with the FAA.

“Garmin then codes this procedure into a format which can be utilized by the FMS in the GTN 650/750. And finally we provide Hughes with an experimental custom database containing this procedure,” he said.

Garmin first added the use of radius to fix legs as one of the leg types used by the GTN through a 2016 software update. The approach procedures developed by Hughes are the first to take advantage of that update.

The GTN’s ability to autonomously control the collective is a standard capability on the GTN, according to Stone.

“This is a natural capability for our FMS’s such as the one in the GTN 650/750. The GTN has the ability to navigate complex flight plans and all ARINC 424 leg types for all phases of flight including departures, arrivals and approach procedures including the missed approach. Provided the aircraft is equipped with a compatible autopilot, the GTN can provide positive course guidance throughout the entire flight plan,” he said.

Another company that was key to assisting Hughes in getting the new procedure developed and ready for flight testing verification is AeroNavData. The Illinois-based provider of navigation data coding is one of only four companies in the world with a type 1 letter of authorization to provide navigation data IFR procedures in fixed and rotary wing aircraft.

Their main role in the project was to take the raw aeronautical data provided by Baur and the Hughes design team – sourced from the actual flying and airspace waypoint creation of the new approaches – and provide verification and validation. They then sent a file to Garmin containing that source data for the new procedure, which was then converted into a binary machine readable format for the GTN flight management computer.

“ARINC has 23 different path terminators that we use to handle coding for RNAV, RNP or any type of PBN procedure,” Aeronavdata CEO Neal Covington said. “In this case, we were incorporating radius to fix legs into the coding of that raw data, which really just does not exist within helicopter operations today.”

Although the company’s navigation database contains more than 6,000 heliports in the western hemisphere, Covington said the majority of requests for design procedures related to RNP are for fixed wing cockpits.

“This opens up a whole new world for helicopter operators,” Covington said. “Almost all of the requests for coding we get related to the use of RNP has always been for fixed wing aircraft at high altitude, there is a whole world of low altitude operations and approaches that could benefit from this.”

Currently the Maryland State Police procedures are for FAA testing and data collection.

The better navigational and positional accuracy or containment through the use of RNP allows helicopters to operate in instrument meteorological conditions, requiring less airspace when supported by the space-based augmentation systems such as WAAS in the US or EGNOS in Europe. Other benefits include the use of vertical guidance which can have minimums of 250 feet height above surface landing and less than three fourths of a mile of visibility.

Helicopter pilots still continue to fly mostly visual flight rules approaches across emergency medical and law enforcement operations, which can be limited and exposed to icing conditions and reliant upon legacy ground-based navigation aids.

Previously, equipage requirements for the use of RNP routes, approaches and departures were resisted to the airlines or business jets equipped with dual flight management computers, dual inertial reference units and more. Today, helicopter operators can benefit from RNP as well with 0.3 COPTER RNP predicated on SBAS or WAAS.

The upgrades for PBN are also readily available today, as all current generation in-production twin engine helicopters feature navigation system packages that are compliant with international RNP helicopter airworthiness requirements.

There have been efforts to expand the use of PBN in commercial aviation operations through programs such as NextGen in the United States and the Single European Sky ATM Research project in Europe, but the focus in those programs has been fixed wing operations. As an example, the PBN information section of the FAA’s NextGen implementation overview features no mention of helicopters or heliports, with all of the focus centralized around Q and T routes and RNAV/RNP approaches in en route airspace for commercial airliners and business jets.

If an operator is RF equipped, they can operate an LPV approach as any other approach. It is simply required to be listed on the operator’s operation specification.

“The need certainly exists to implement modern navigation procedures for helicopter operators that have been enjoyed by the airline community as well. Now, we just have to keep proving it and show how it can change the way we view the heliport flight environment.”

Airliner Style PBN for Helicopters

Post by Alyce Shingler on , updated on January 24, 2020

WOODROW BELLAMY III

Sitting co-pilot during a demonstration of the world’s first-ever helicopter radius-to-fix landing procedures.

A collaborative use of instrument flight rules procedures and new flight control systems from Hughes Aerospace, working with the FAA, Garmin and AeroNavData, has produced the world’s first use of radius to fix segment coding for a helicopter landing procedure.

In December 2018, Hughes Aerospace CEO Chris Baur completed a flight validation of new helicopter IFR procedures using RF for a route consisting of eight different heliports between Morgantown, West Virginia, and Baltimore, Maryland. Baur and the air navigation service provider design navigation procedure design team from Hughes developed the low-level helicopter instrument flight rules procedures after a week-long route verification of the new procedures with the FAA.

The new procedures use the latest FAA criteria featuring Required Navigation Performance (RNP) 0.3 and RF segment coding. RNP is a performance-based navigation concept using internationally accepted specifications that create precise and determined pathways for fixed and rotary-wing aircraft.

RNP 0.3 is the requirement for an aircraft’s navigation system to be capable of calculating its airborne position within a three-tenths of a nautical mile, and it is the International Civil Aviation Organization’s acceptable level of accuracy for the use of RNP in all phases of helicopter flight. Operators seeking to use RNP 0.3 today are required to obtain special authorization from their local civil aviation regulator.

Baur provided an in-the-cockpit flight procedure validation to Avionics International demonstrating the use of RF approaches at one of the hospitals along the new route – Garrett County Memorial Hospital. His company is using a newly-purchased Robinson R44 featuring high resolution twin glass displays, a digital autopilot with stability augmentation and ADB-B In and Out.

One of the central components enabling the new RF approaches is the R44’s Garmin GTN 650H flight management computer. The FMS featured a special navigation database reserved for flight testing.

“This is historic,” Baur said, as he removed his hands from the controls and watched the GTN 650 autonomously control the collective from waypoint to waypoint, as depicted in the approach chart provided below.

As the R44 glided from waypoint to waypoint, a Maryland State Police helicopter’s ADS-B positioning was visible, so Baur opted for the missed approach. By selecting the test procedure his team developed from within the system’s navigation database, the flight management system populated a new set of waypoints, a missed approach using an RF segment arc from HADJI to BRAZY.

It’s the type of flying that Baur, a 30-year commercial airline pilot who is also type rated across multiple helicopter variants and runs an air navigation service provider, said is common in the commercial airline world but still limited to small pockets of commercial helicopter operations.

“I’m really trying to bring the type of predictable approach paths and procedures from the commercial airline world to civilian helicopter operations,” he said.

“You can use RF turns to mitigate heliport obstacles and obtain lower landing minimums at. It’s also wind independent, we noted the wind direction and velocity on each RF leg and recorded bank angles as well. The highest bank angle at any time within this approach was nine degrees. Going forward we will get even more aggressive about how much bank angle we can use. Typically in any helicopter PBN procedure design you want to use less than 20 degrees of bank angle.”

The effectiveness of the RF leg was shown during the first flight demonstration Baur performed in December, which featured cross and tail winds ranging from 20-30 knots. Even in those conditions, the helicopter was able to perform with a cross track error of just 0.00-0.01, or 60.7612 feet.

The procedure was created featuring RNP 0.3 and radius-to-fix segment coding as a demonstration procedure designed for use by the Maryland State Police.

Baur’s experience flying commercial airliners showed him that through experience the use of RF legs in en route airspace has little-to-no benefit for fixed wing operations. However, at lower altitudes, where helicopters need to fly within defined paths and avoid encroaching on nearby airspace when approaching heliports with terrain and environment obstacles, it can help the helicopter fly the approach more efficiently, especially in IFR conditions.

He sees the use of RF legs in PBN procedures holding massive benefits for reducing fuel and the number of track miles flown, as well as decreasing communication between pilots and controllers attempting to complete point in space helicopter landings.

This type of advanced use of RNP though remains limited within global commercial and civilian helicopter operations, the bulk of which exist in North America and Europe. However, there are efforts to continue its expansion, which can only occur with the type of collaborative effort it took to create the new procedures.

“In these cases, Hughes Aerospace develops a custom procedure, such as the one landing on the helipad at Garrett County Memorial Hospital, and provides this electronically to Garmin,” Bill Stone, senior manager of business development for Garmin’s aviation division said, describing the process of getting the new procedure into the Hughes R44 for flight testing and procedural validation with the FAA.

“Garmin then codes this procedure into a format which can be utilized by the FMS in the GTN 650/750. And finally we provide Hughes with an experimental custom database containing this procedure,” he said.

Garmin first added the use of radius to fix legs as one of the leg types used by the GTN through a 2016 software update. The approach procedures developed by Hughes are the first to take advantage of that update.

The GTN’s ability to autonomously control the collective is a standard capability on the GTN, according to Stone.

“This is a natural capability for our FMS’s such as the one in the GTN 650/750. The GTN has the ability to navigate complex flight plans and all ARINC 424 leg types for all phases of flight including departures, arrivals and approach procedures including the missed approach. Provided the aircraft is equipped with a compatible autopilot, the GTN can provide positive course guidance throughout the entire flight plan,” he said.

Another company that was key to assisting Hughes in getting the new procedure developed and ready for flight testing verification is AeroNavData. The Illinois-based provider of navigation data coding is one of only four companies in the world with a type 1 letter of authorization to provide navigation data IFR procedures in fixed and rotary wing aircraft.

Their main role in the project was to take the raw aeronautical data provided by Baur and the Hughes design team – sourced from the actual flying and airspace waypoint creation of the new approaches – and provide verification and validation. They then sent a file to Garmin containing that source data for the new procedure, which was then converted into a binary machine readable format for the GTN flight management computer.

“ARINC has 23 different path terminators that we use to handle coding for RNAV, RNP or any type of PBN procedure,” Aeronavdata CEO Neal Covington said. “In this case, we were incorporating radius to fix legs into the coding of that raw data, which really just does not exist within helicopter operations today.”

Although the company’s navigation database contains more than 6,000 heliports in the western hemisphere, Covington said the majority of requests for design procedures related to RNP are for fixed wing cockpits.

“This opens up a whole new world for helicopter operators,” Covington said. “Almost all of the requests for coding we get related to the use of RNP has always been for fixed wing aircraft at high altitude, there is a whole world of low altitude operations and approaches that could benefit from this.”

Currently the RF approach procedures remain reserved only for flight testing and validation, and all of the heliports along the new route are still reserved to VFR operating conditions.

The better navigational and positional accuracy or containment through the use of RNP allows helicopters to operate in instrument meteorological conditions, requiring less airspace when supported by the space-based augmentation systems such as WAAS in the US or EGNOS in Europe. Other benefits include the use of vertical guidance which can have minimums of 250 feet height above surface landing and less than three fourths of a mile of visibility.

Helicopter pilots still continue to fly mostly visual flight rules approaches across emergency medical and law enforcement operations, which can be limited and exposed to icing conditions and reliant upon legacy ground-based navigation aids. That continues to make any of the aspects of the advanced use of RNP that Hughes demonstrated very limited in the world of helicopter operations.

Equipage requirements for the use of RNP approaches include dual flight management computers and two inertial reference systems. Pilots also need specialized aircrew training and must also demonstrate their ability to do things like use the containment accuracy of WAAS demonstrated at 0.3 RNP.

The upgrades for PBN are also readily available today, as all current generation in-production twin engine helicopters feature navigation system packages that are compliant with international RNP helicopter airworthiness requirements.

There have been efforts to expand the use of PBN in commercial aviation operations through programs such as NextGen in the United States and the Single European Sky ATM Research project in Europe, but the focus in those programs has been fixed wing operations. As an example, the PBN information section of the FAA’s NextGen implementation overview features no mention of helicopters or heliports, with all of the focus centralized around Q and T routes and RNAV/RNP approaches in en route airspace for commercial airliners and business jets.

While the new RF procedure is ready and certifiable today, it remains unpublished and unavailable to suitably equipped helicopters without obtaining special authorization. Moving forward, Hughes is working on the development of three additional helicopter prototype procedures at three new heliports and will be conducting similar demonstration flights in visual meteorological conditions to collect data and identify any obstacles to deploying WAAS–enabled helicopter PBN procedures.

“The need is certainly there for bringing more airliner style procedures to the helicopter PBN world,” Baur said. “Now, we just have to keep proving it and show how it can change the way we view the heliport flight environment.”

http://digitaledition.rotorandwing.com/heliexpo-2019/airliner-style-pbn-for-helicopters/