A WAAS buy-in adds real mission capability and workload reduction. But walk-away costs vary wildly with glass cockpits taking the biggest hit.

By Larry Anglisano

In February 1996, the FAA’s 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."

WAAS pays off for instrument flying where LPV approaches offer near or equal-to ILS minimums with rock-solid stability. GPS approaches in general are becoming the only option for some airports. The economics of WAAS in the panel makes little sense for a VFR-only aircraft.

Today’s IFR GPS installations are all about the augmented WAAS signal that’s worthy of sole-means navigation. They’re 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. It’s About Signal Quality …