[Avionics Magazine 04-12-2016] United Airlines recently completed a project in the Federated States of Micronesia designed to take advantage of the advanced navigation capabilities of its airline fleet, increase safety, and generally make United pilot's lives easier there. Working with FAA and ICAO’s third party Air Navigation Service Provider (ANSP) Hughes Aerospace Corp., the airline is now using Micronesia's first ever Area Navigation (RNAV) Required Navigation Performance (RNP) procedures at Pohnpei International Airport.
RNAV RNP final approach at Pohnpei International Airport. Photo: Hughes Aerospace.
United is one of the only international carriers servicing the 6,800-foot runway at Pohnpei, and has needed the new procedures for years. The airport has no radar coverage, is surrounded by challenging terrain and has been limited ground-based and RNAV GPS approaches. With this in mind, the airline decided to take advantage of the advanced RNP navigation capabilities featured on its fleet of Boeing 737s.
"United has been flying to the islands of Micronesia for many years. Many of the islands, including Pohnpei, only had ground-based approaches known as Non-Directional Beacon (NDB) approaches. The FAA did add RNAV (GPS) approaches but they generally have paths across the ground similar to the NDB. In the case of Pohnpei, this meant the approach was at an angle to the runway. The new procedure offers a straight in approach so the pilots are lined up with the runway when they break out of the clouds," Ron Renk, chief technical pilot at United Airlines told Avionics Magazine.
The new RNP procedures at Pohnpei provide United pilots with vertical guidance down to the runway surface, lowered instrument approach minimums from 920 feet and 3 miles, to 259 feet and 1 mile. Hughes Aerospace worked with United to complete the design, validation and publishing of the new procedures within four months, and the airline has now begun using them.
United will also now benefit from reduced fuel burn and carbon emissions at Pohnpei.
"The new approach offers many benefits over the approach it supplements. The flight path is optimized with is connection to the enroute airspace, saving fuel and CO2 emissions. It also has lower minimums, meaning we can more reliably get into Pohnpei even when there is [bad] weather. By far though, the best thing for us is the increase in safety offering a straight in approach versus the offset RNAV (GPS) approach," said Renk.
Chris Baur, CEO of Hughes Aerospace, worked with Renk as a third party service provider to lead the deployment of RNP at Pohnpei. He told Avionics Magazine that the use of the new procedures are projected to lead to some significant fuel savings for United as well.
"We wanted to provide a stabilized approach, that lines up with the runway with vertical guidance to the surface, and the other thing we did is to reduce the amount of track miles to fly this procedure, by pulling them in closer to the island. We think that this procedure should save the airline $100,000 to $150,000 per year in fuel costs," said Baur. "When we design a procedure, we try to get the lowest minimums at the highest RNP value, meaning we try to get the lowest minimums at a .3, so that the largest number of aircraft can have success operating an approach. But that’s not always possible, because of terrain, obstacles or other situations."
The new approaches deployed at Pohnpei are similar to PBN procedures that the FAA has been deploying throughout the U.S. National Airspace System (NAS) under its NextGen program. According to the agency’s latest reported information, 59 percent of air transport category registered aircraft in the U.S. are equipped to perform RNP 1 with curved path procedures, while nearly 100 percent are equipped with avionics to fly more basic forms of PBN such as RNAV 1, RNAV 2 and RNP Approach.
Baur said one of the keys to deploying the new procedures in Pohnpei, is the process that the FAA has developed for redesigning airspace to allow properly equipped aircraft to choose the best path and approach to airports with challenging terrain.
"Even 10 years ago, the avionics for RNP were not consistent throughout the industry. And that’s changed and evolved significantly over the last 10 years. The FAA's regulatory process has evolved significantly as well. That allows you to develop these types of procedures," said Baur.
"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.