As most of us know by now, WAAS is not a name from the Netherlands; it’s an acronym for the latest GPS enhancement, the Wide Area Augmentation System. The result is a more-accurate GPS signal—down to less than three meters. Think of it as GPS on steroids.

In addition to providing a much more accurate en route signal, more direct flights, simplified on-board equipment and eliminating many costs associated with maintaining a large and diverse system of ground-based navaids, WAAS will provide a tremendous increase in the number of precision (or near-precision) approaches. At least that’s the plan. First, let’s discuss why it’s needed.

Siting the basic ILS antenna array requires a relatively unobstructed area. If terrain is sloping or uneven, reflections can create an uneven glidepath causing unwanted needle deflections.

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