RNAV,GPS IFR question?

[Maximillian_Jenius]

Studying for my IFR test when it comes to question about GPS/RNAV they only talk about procedures such as RNAV/GPS DP's and arrivals. Are there RNAV/GPS waypoints for the enroute segment of flight. Or enroute at flight level is that all purely ground based navigation via VOR's?

[Doug Taylor]

There are both waypoints formed from ground-based equipment and also waypoints that are purely RNAV.

[Maximillian_Jenius]

Originally Posted by Doug Taylor

There are both waypoints formed from ground-based equipment and also waypoints that are purely RNAV.

By GBN WP do you mean VOR's and fixes at intersections? If so I was under the understanding (in my limited knowledge) that WP were only used in RNAV/GPS. Fixes being purely GBN like VOR's.

[aloft]

He means that an RNAV/GPS route can be defined by waypoints colocated with ground-based navaids, or by waypoints colocated with unicorn ranches. Since lots of GPS approaches are "overlay" approaches--meaning they simply replicate a non-precision approach with waypoints instead of navaids, radials and DME fixes--it often makes sense to route to a navaid or other ground-referenced fix when flying GPS-direct just to integrate with the terminal structure.

[BobDDuck]

Waypoints that are strickly RNAV are 5 letters long and have to be phoneticly pronouncable (although there are some that aren't that easy). Ground based navigation stations (VORs, NDBs, LOCs etc) can be tuned in using a radio frequency and tracked that way, or for the most part also can be entered into a GPS/FMC using their letter identifier and become a fix in the RNAV world. As far as pure GPS fixes used for enroute flight? I don't think you will find too many on victor or jet airways as they need to be navigatble by /a aircraft, although now that I think about there are some (fixes that are marked by an "x" on a jep chart). Also in the enroute stage it is pretty common to be cleared direct to a VOR when you are too far to pick it up. For RNAV aircraft it is a simple matter of throwing the identifier in the box and pressing NAV. The /a airplanes will generally ask for a heading and get a response like "fly 040, direct XXX when able." Is that what you were asking?