In a meeting with aviation experts, the terms black routing and red routing were discussed. What are they? From the discussions I was able to put together that either the TMU (Traffic Management Unit) or the controller can see two routes for a flight, a cleared route (black route?) and an agreed route (red route?).

I don't know what display they were referring to and if it was the controller that was looking at the display or if it was some traffic management display.

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    $\begingroup$ With no other information, I would think that one is the planned (ideal?) route and the other is the actual route, but I have no idea which one would be which. $\endgroup$
    – mkennedy
    Commented May 25, 2018 at 22:00
  • $\begingroup$ It would be useful if you could add a geographical tag to this question, bear in mind this is a global website. The terms may very well be specific to a certain region. $\endgroup$ Commented Sep 2, 2020 at 15:34
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    $\begingroup$ Why didn't you ask in the meeting?! $\endgroup$ Commented Oct 2, 2020 at 17:42

1 Answer 1


Here's the history, at least for the US.

When I hired on, way back in 1985, the FAA had printers based on IBM Selectric mechanisms. They had a two-color ribbon, red and black, and a typeball with capital letters in two sizes, plus a few special symbols.

When a strip was printed, color could be selected by the computer for certain items. Callsigns on eastbound aircraft, for instance, were printed in red. A red route appeared when an aircraft filed a non-preferred route to or from certain airports.

In the US, red is used for a PLANNED route or restriction - something the controller SHOULD do, but hasn't accomplished yet. As an example, if you filed KBFF..KDEN in your C650, the strip would reflect your filed route, but the computer would include a route over LANDR, like this - "KBFF.LANDR1.KDEN" (routing would be over AALLE, today)

That route would be printed in red, to alert the controller, and was the forwarded route. In other words, all subsequent positions would show that route in black, with no reference to the original filed route.

The controller issuing the clearance is expected to use the red coordinated route. If they choose not to (such as for a MEDEVAC), they must update the flight plan to force processing of the original route.

Today, there are no "red routes" per se, if you observe a preplanned route in EDST, it's highlighted in blue. Our strips no longer have two-color capability, so "red" text is now printed in black with a grayscale highlight.

The jargon, however, lives on!

To further address your example, if both a red route and black route exist in the system for a particular aircraft, that means the preferred route has NOT been issued, and some action must be taken. The controller with responsibility for meeting the restriction for that route will issue it, or force the computer to override the red route. Either way, it ensures that subsequent sectors get the right information.

  • $\begingroup$ The joke these days has to do with "old guys" calling blue routes in EDST "red", because we've all gone over edge. $\endgroup$
    – atc_ceedee
    Commented May 9, 2021 at 18:14
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    $\begingroup$ In the terminal environment we would get what's called a Preferential Departure Route (I think) on the strip. The filed route KBFF KDEN would be bumped down a line, and above is the suggested route, enclosed in plus signs: +LANDR1 KDEN+. Only the portion of the route that needs to be modified is printed above. My facility's SOP is to highlight the plus signs in red pencil to draw attention to the PDR. $\endgroup$
    – randomhead
    Commented May 9, 2021 at 18:15
  • $\begingroup$ @randomhead, you'd be correct in the center environment, as well. That's the same way we display the route. I took a shortcut in my explanation. You can also put your own "red route" in, by doing a route amendment with the plusses. If I wanted to take the BFF departure over RAMMS, for instance, I could type "KBFF+..LAR.RAMMS1.+KDEN", and it will show my new route as the preferential arrival route. ERAM might still tell me to do otherwise, when the flight plan is activated. $\endgroup$
    – atc_ceedee
    Commented May 9, 2021 at 18:42
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    $\begingroup$ Thanks for plugging this hole in history, and welcome to SO! (Long live sed and awk, too.) $\endgroup$ Commented May 9, 2021 at 19:43
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    $\begingroup$ I really appreciate how you thoroughly explained this answer! Thank you kind stranger. $\endgroup$
    – Alessandro
    Commented May 11, 2021 at 14:18

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