DESIGNING THE APPROACH CUSTOMIZED INSTRUMENT PROCEDURES Post by Alyce Shingler on October 20, 2019, updated on October 20, 2019 BY RICH PICKETT SEPTEMBER 26, 2019 FEATURE http://twinandturbine.com/article/designing-approach-customized-instrument-procedures/ 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 HeliportsFor 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 AerospaceBehind the Scenes LookI 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.