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Upgrading to WAAS: Only Few Options Exist

In February 1996, the FAAs Technical Standard Order (TSO) C129 put IFR GPS navigation on the map. It was a complex installation with equipment that was quirky to program, but early adopters gained GPS-direct flight plans and GPS approaches-even though GPS was "supplementary navigation." Todays IFR GPS installations are all about the augmented WAAS signal thats worthy of sole-means navigation. Theyre still a source of confusion and expense, but WAAS installations yield impressive automation and capability. Before you decide if WAAS is for you, you need to understand some behind-the-scenes facts and why you could be disadvantaged without WAAS GPS in your aircraft.

Larry Anglisano
Verified

In February 1996, the FAAs Technical Standard Order (TSO) C129 put IFR GPS navigation on the map. It was a complex installation with equipment that was quirky to program, but early adopters gained GPS-direct flight plans and GPS approaches-even though GPS was “supplementary navigation.”

Todays IFR GPS installations are all about the augmented WAAS signal thats worthy of sole-means navigation. Theyre still a source of confusion and expense, but WAAS installations yield impressive automation and capability. Before you decide if WAAS is for you, you need to understand some behind-the-scenes facts and why you could be disadvantaged without WAAS GPS in your aircraft.

Its About Signal Quality

WAAS and precision-GPS equipment, procedures and regulations are covered in TSO C146a. The technical and operational benefits of a WAAS interface are many, and the new WAAS GPS engines, processors and software are reliable and highly accurate. WAAS not only enhances GPS accuracy but also corrects the errors in GPS signals caused by ionospheric effects.

WAAS provides less than 1.5-meter horizontal accuracy and 3-meter vertical accuracy. Class 3 WAAS sensor capability means no other navigational gear is required. If this sounds like putting all the eggs in a single basket, it is. These owners are relying completely on quality installations.

Operational WAAS also doesnt require user to check RAIM-receiver autonomous integrity monitoring-which was an early

Larry Anglisano

Editor in Chief Larry Anglisano has been a staple at Aviation Consumer since 1995. An active land, sea and glider pilot, Larry has over 30 years’ experience as an avionics repairman and flight test pilot. He’s the editorial director overseeing sister publications Aviation Safety magazine, IFR magazine and is a regular contributor to KITPLANES magazine with his Avionics Bootcamp column.