My understanding of precision was both lateral and vertical guidance. If a GPS approach with WAAS provides both, why is it still considered non-precision?

  • $\begingroup$ I believe I've seen the explanation somewhere around the site already, but it is not present in the similar question the search manages to find, aviation.stackexchange.com/questions/6341/… (it only says it is non-precision, but not why). $\endgroup$
    – Jan Hudec
    Apr 4, 2016 at 11:35
  • 5
    $\begingroup$ @JanHudec This one? $\endgroup$
    – Pondlife
    Apr 4, 2016 at 13:02
  • $\begingroup$ @Pondlife, yes, that one looks like a good duplicate. $\endgroup$
    – Jan Hudec
    Apr 4, 2016 at 13:22
  • $\begingroup$ @JanHudec I think it's a dupe, but unfortunately the only answer on the other question doesn't make any sense (to me), unless I missed something. That doesn't change the dupe thing, of course. $\endgroup$
    – Pondlife
    Apr 4, 2016 at 13:48
  • $\begingroup$ @Pondlife the answer that is linked states that a non-precision approach with vertical guidance is considered that because onboard instruments compute the planes location. However with WAAS, there are ground based stations outside of the aircraft which help compute this. $\endgroup$
    – jskypilot
    Apr 5, 2016 at 10:56


Browse other questions tagged .