7
$\begingroup$

I found in our data a route formatted with dots instead of with spaces and DCTs. Example:

DTW..LAYNE.DXO006.BNNET.YQG341.DIRKS.J38.GRB/0052

What is the name of this format?

Second question: Sometimes instead of .. and . after the departure airports there is ./.—what does it mean? Example:

KIAH./.ABCD..BEREE.BEREE1.KDFW
$\endgroup$
1
  • $\begingroup$ Note that in your DTW example, DXO006 and YQG341 are not points in space but specified radials off of VORs. This is why they use single dots to connect to the fixes BNNET and DIRKS. $\endgroup$
    – randomhead
    Commented Jul 27, 2021 at 0:04

1 Answer 1

6
$\begingroup$

This is an ATC routing format, introduced long ago, with the IBM 9020 mainframe. The dots are element separators, used because spaces would signify a new field in the flight plan. Two dots separate like elements (ABCD..BEREE would be two points, J107..J148 would be two airways) and single dots separate unlike elements (BEREE.BEREE1 is a fix followed by a route [in this case a STAR with the fix name in it]).

Two dots do not necessarily mean "direct;" all they signify is a connection between two like elements. But it is true that when the two like elements are both points in space, rather than routes, the meaning is "direct to the next point in space."

The ./. construct is called a tailoring symbol, and is used to indicate previous routing which has been dropped (PANC./.DDY..MBW.RAMMS5.KDEN) because it is no longer needed (there may have been ten elements or more between PANC and DDY). In other words, once your flight passed ABCD, nothing between your departure point and ABCD was needed anymore.

You may also see, on a flight plan strip, three stars: PANC./.DDY..MBW***KDEN. This indicates additional routing which was not printed on the strip due to a lack of physical space. If you request a "full route" for the aircraft you can see the actual route instead of ***. (This is not the case for the tailoring symbol, which will not be expanded out on a full-route strip.)

Also, for an added bonus, the /0052 at the end of your route is the estimated time enroute (in hours and minutes) for an inactive flight plan, or your estimated time of arrival (in UTC) for an active flight plan.

There's some history to add here, for controllers, as well. I knew a gentleman by the name of Frank Cox who actually worked on the IBM9020 CHI (Computer-Human Interface) as a Radar Input SME. He told me the reason why the radar route key required spaces between elements (and routes were not allowed), while the AM (amendment button) format required dots between elements-

"I worked in DC with the radar team, in the R&D building, on the second floor. The D-Side team worked in the same building, same floor, two doors down the hall. We never talked to each other."

$\endgroup$
7
  • $\begingroup$ I thought . was for connected elements (like the fix to enter/exit an airway) and .. was for direct? $\endgroup$
    – StephenS
    Commented Jul 26, 2021 at 20:23
  • 2
    $\begingroup$ ".." separates like elements (J123..J456, DIR..ECT) while "." separates dissimilar elements (J123.DIR, ECT.J456). $\endgroup$
    – RetiredATC
    Commented Jul 26, 2021 at 20:40
  • 2
    $\begingroup$ @StephenS In case case of, say, 2 VORs, ABC..DEF, the .. happens to BE direct routing from the one to the next, but that isn't the definition of the .. there. Just happens to match. $\endgroup$
    – Ralph J
    Commented Jul 26, 2021 at 20:48
  • $\begingroup$ @RalphJ Got it; thanks! $\endgroup$
    – StephenS
    Commented Jul 26, 2021 at 21:09
  • $\begingroup$ Thanks for the assist, randomhead! $\endgroup$
    – atc_ceedee
    Commented Jul 27, 2021 at 13:19

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .