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.


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.

  • $\begingroup$ So basically ATC still needs us flying preset paths so they only have to manage high-angle conflicts at intersections rather than low-angle conflicts everywhere, and RNAV just means those paths are more numerous (and hopefully more optimal) than before? $\endgroup$ – StephenS Oct 31 '18 at 15:27
  • $\begingroup$ Good answer @JohnK - I am a former controller at an ARTCC, TRACON, and TWR as well as a retired pilot (B737/757/767). I was trying to formulate a good answer to the OPs question, but could not have said it any better than your answer. I'd like to add that I'm confident that in 20 years or so, with the advancement in Pilot/Aircraft/Controller electronic data links/avionics, etc, (requiring less [very little] human involvement in separation and sequencing) more random and efficient routing can be achieved. But at this time, ATC is still 98% a human task. $\endgroup$ – 757toga Oct 31 '18 at 17:19
  • $\begingroup$ Thanks @757toga I tried out for ATC in Canada once in the 80s and took the initial screening exam in a room with about 50 candidates. 50 multi-guess questions relating to 25 radar screen diagrams where you had to look at tracks and a table of their routes/altitudes and determine if there would be conflicts. I didn't track the time and the exam ended when I was at question 46. I got 2 of 46 wrong, thought 88%, great, the pass was 80%, but found out later you had to get 90% to be selected. If I'd just randomly answered the last 4 questions in the final seconds I'd probably have made it. $\endgroup$ – John K Oct 31 '18 at 17:38
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    $\begingroup$ Note that nowadays with improvements of computers assisting the controllers, completely free routing is being used more and more. Austria has already deleted airways from all its airspace except the narrow Tirol “tail” and whenever I try to compare flight routes (from FR24) over Czechia or Germany with airways on SkyVector map, there is usually no correlation at all. $\endgroup$ – Jan Hudec Nov 1 '18 at 20:16
  • $\begingroup$ What amazes me is how RNAV was originally developed in the late 60s during the Integrated Circuit era prior to the microprocessor, coming up with a way to virtually relocate VORs using analog solid state electronics and not with software. $\endgroup$ – John K Nov 2 '18 at 1:25

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: enter image description here

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

enter image description here

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    $\begingroup$ This doesn't answer the question. $\endgroup$ – TomMcW Oct 31 '18 at 13:00

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.


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