I'm listening to an LiveATC stream for the Seattle Tacoma airport.

I keep hearing things like "push approved on the blue line".

I'm pretty sure I've heard orange, blue, and green as colors.

What does this mean?


1 Answer 1


If Seattle works anything like a number of major German airports, these instructions refer to literal coloured lines on the ground.

Taxiway markings are usually yellow, but some large airports have started to use different colours for marking taxilanes on the apron ("ramp"). This is a way of maximizing use of available space in areas used by many differently sized aircraft.

One example is Munich, Germany (EDDM) where yellow, orange and blue taxi lines are used.

enter image description here

(snippet from APDC EDDM, from DFS)

Two medium sized aircraft can pass eachother when following the blue and orange lines, whereas a larger aircraft will have to follow the central yellow line, thus taking up the entire width of the taxiway.

As @ymb1 pointed out in a comment, the system in KSEA appears to be similar. The colour of the taxilines are varied, and signs (or markings on the ground) describe the colour code for certain taxi lines:

enter image description here

  • $\begingroup$ It looks like all of the actual taxilanes on the ramp at SEA are the same color. There are some different colors for the lines directing traffic into/out of some of the stands, though, so you're probably right. However, I don't see any blue lines; just orange, red, or dashed green/orange. And the red ones only appear to be at a few remote stands, not at the passenger gates. Of course, it's possible that Google's imagery is out-of-date. $\endgroup$
    – reirab
    Sep 4, 2017 at 17:31
  • $\begingroup$ @ymb1 Ah, nice find. I guess the imagery I was seeing on Google Maps is indeed old then, as I don't see those lines there. $\endgroup$
    – reirab
    Sep 4, 2017 at 19:51

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