==This article is about WAAS== 
 In this revision, I pulled a large section out of the History/approaches section. Most of it was a bit tangent to the subject of WAAS, maybe it could be distilled to something smaller and more readable. I think this article should focus on the capabilities, limitations, history, operation and future of WAAS. Comparison of WAAS with other systems is probably acceptable as long as it's very concise and doesn't stray from the subject WAAS. We don't need to explain GPS, ILS, MLS and every other radio navigation system in this article. I suppose consumer usage of WAAS could be mentioned, but WAAS was made for aviation usage, so that should be the focus of this article.