Pilot's Guide to Avionics 2011-2012 - 20

PILOT’S GUIDE

WAAS/GPS Benefiting Early Adopters
S T O R Y B Y D A V E H I G D O N

minor milestone passed largely unnoticed back in December 2009 — the decade anniversary of when the first signals for a new precision navigation system began streaming down from space, sent from special satellites parked high overhead . This first step in a fast march to establish the widearea augmentation system supported a broad mission to increase the accuracy of the main global positioning system constellation . A decade ago, WAAS still faced multiple challenges, first among them merely getting the infrastructure fully in place and functional . In parallel, WAAS also faced rigorous testing to affirm its functionality and reliability, no easy task amid seemingly never-ending funding pressures . And, then there was the issue of the flying public . For WAAS to mean anything, operators and aviators alike faced the costs of new equipment capable of using the new system in the real world — a world where approaches and procedures had to be developed and established to achieve the big payoff for users and regulators . Today, the payoff exists and continues to expand . WAAS/GPS now supports more precision instrument approaches than the venerable instrument landing system, as the FAA recently reported . New high-precision arrival and departure procedures help air carriers trim minutes from their en-route times, contributing to millions in fuel savings, smoother traffic flow and improved arrival rates in the poorest weather . Today, according to FAA Administrator Randy Babbitt, more than 32,000 aircraft fly WAAS-equipped, -capable and -approved . And, the number of WAAS-equipped aircraft and WAAS-supported procedures continue to grow daily, with aircraft OEMs offering upgrades to older aircraft and avionics manufacturers offering replacement, retrofit and new-installation products that embrace WAAS . Quite a journey for a decade .

Getting Here from There A decade ago, GPS already supported en-route and terminal navigation with accuracy high enough to support non-precision instrument approaches at greater accuracy and usually with lower minimums than any available groundbased guidance . The accuracy promised from WAAS-enhanced GPS signals promised significant advances in accuracy, benefiting navigation, surveying and mapping, as well as something akin to the Holy Grail of operations within aviation circles, the big promise of super-accurate satellite navigation: satelliteguided precision instrument approaches with accuracy comparable to the gold standard of the ground-based approaches, the instrument landing system or ILS . The first broadcast of WAAS signals in December 1999 opened the door to the FAA’s intense testing while establishment of the ground network proceeded . Thanks to progress made, the FAA officially commissioned WAAS for aviation use in July 2003 . In 2004, the agency granted TSO approval to the first WAAS/GPS navigator capable of using the new precision signal, the Garmin GNS 480 . With this door open, the impact of WAAS enhancement grew rapidly and continues unabated . With the system capability now firmly in place for more than seven years and the avionics growth since its commissioning, WAAS capability permeates through the selection of GPS navigators . Manufacturers provide WAAS capability on GPS receivers ranging from handheld navigators to turbinecockpit flight management systems — and pretty much everything in between . WAAS even enhances aviation items, such as electronic flight bags with the navigation capability and geo-reference aircraft icon on the chart or plate . Unfortunately, a, significant problem plagues the WAAS universe, one authorities hope to resolve later this year . But this issue, a satellite problem, helped renew discussions about the need for a backup system for GPS and WAAS . Fortunately, this problem seems to have limited impact on the nearly 2,100 runway ends boasting the new instrument

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Pilot's Guide to Avionics 2011-2012

Table of Contents for the Digital Edition of Pilot's Guide to Avionics 2011-2012