Why do RNAV airways exist?

Question

I assume there's some stupidly obvious reason that I'm missing, but why bother creating RNAV airways when I thought the entire point of RNAV was not needing to fly along a suboptimal preset path?

I can see the need for waypoints, especially around the corners of restricted airspace that you'd need to dodge rather than just flying direct everywhere, but I'd think an RNAV flight plan would just be a handful of such critical waypoints--no "airways" needed.

Answer 1

RNAV freed aircraft from the airways that were already in place that may have zig zagged from VOR to VOR, but with the limitations of the ATC system based on human controllers, it is still desirable to keep most aircraft on a "road network" so to speak to make it easy to manage separation, so RNAV airways were created between major centers that provide straighter roads between cities you might say.

Try to imagine thousands of flights going hither and yon all on their own random tracks, instead of being fed along specific airways, without a bank of supercomputers to manage the separation, and you can see the problem that the RNAV airways solved.

Answer 2

You are partially correct, first of all they are called "RNAV routes" not "RNAV airways" and yes the entire point of RNAV was not needing to fly along a suboptimal preset path but that was because of the fact that you flight plan had you flying directly over the navigational beacons. Like this:

RNAV routes allow more efficient flight by connecting random positions by selecting routes more freely, in addition to shortening the flight distance than conventional airways. RNAV routes also provide you with following features:

1) Expansion of airspace capacity : Reduces lateral separation, allowing to double or quadruple the tracking of flight paths.

2) Reduce flight time and distance

3) Reducing flight cancellation and delay

Answer 3

RNAV airways are there for several reasons: (Speaking as a US controller and instructor)

1. Radar performance. Radar is not everywhere, and neither is ADS-B. Regulations require GNSS aircraft to be established on valid point-to-point routes, either using charted fixes within certain distance criteria, or flight checked airways unless in radar contact. This aids in search and rescue.
2. Flow control initiatives. Imagine, if you will, 100 air carrier aircraft all trying to get to KORD (Chicago O'Hare) at exactly the same time. Can't be done. Routes are established that Chicago ARTCC requires these aircraft to be on, and with miles-in-trail initiatives to keep the aircraft in an orderly flow.
3. Weather. Weather is constantly on the move, and issuing airway routing is often easier than issuing point-to-point, and, it's easier to understand. It's also faster, and less prone to error.
4. Transitional flight. Airways have built-in transitions to standard terminal arrival routes (STARS) and to approaches. Verbiage is shortened (again) when using them, because a controller does not have to issue an altitude restriction to a pilot when clearing an aircraft on a Standard Terminal Arrival Route, because the altitudes, speeds, and other instructions are printed on the STAR. Similarly, altitude restrictions can be omitted on an airway transition to an approach, whereas, on a direct route, a restriction must be issued.

Whenever a procedure (in this case, an airway) can be used to reduce confusion, conflictions, and verbiage, it's a good thing.