Taxi-Sign Nomenclature: If I Wanted Alphabet Soup, I'd Have Called Campbell's!

Hi,

 

I have a question about standard nomenclature rules for taxi signs and how they apply in different situations. I have several picture/diagram examples I want to show to illustrate my questions, but before doing so, let me ask the basic questions in brief form first:

 

1. Should the "current location" taxiway designator (the one that's yellow with a black background), ALWAYS be justified left on the taxi sign, and all other directive taxiway designators then come afterward from left to right—in clockwise order from lower-left to lower-right? Or should the "current location" designator be justified center, and all directives left are to the left of the location designator, and all directives to the right are to the right?

 

2. In the case of a taxiway intersection where the one that you're on changes letters AFTER passing through the next taxiway intersection, should the new letter be indicated with an up-arrow directly next to the current location indicator, or after the cross taxiway has been labeled? Should the straight up arrow be placed to the left or right of the indicator for a new taxiway straight ahead?

 

3. In the case of a complex intersection with multiple taxiways all intersecting at the same point (and NOT changing names after passing through the intersection), should the ones pointing left of the current location designator be separated from the ones pointing right? Or in that case should each letter share two arrows—one to the left of the letter pointing left, the other to the right of the letter pointing right?

 

4. In the case of a complex intersection with multiple taxiways all intersecting at the same point (but the names DO change after passing through the intersection), would it ever be permissible to have the two letter pairs for each side of the intersection be placed right next to each other, with their respective directive arrows pointing in opposite directions, or are separate letters always kept totally separate?

 

If you wish to avoid the rest of this long post, and get the gist of what I'm asking above, then spare yourself the long details below. But if some of what I asked above wasn't quite clear, this will probably make more sense when I show pictures:

 

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1.

 

 

In this simple 3-way intersection, choice #1 favors the locational designator being centered with the directional indicator being to the left. Though since there's only two of them, hard to establish a center. Choice #2 favors the current location designator as being justified left (no matter what)—and all directional indicators being to the right of the one that establishes current location.

 

So which one is actually correct? #1 seems more intuitively correct to me, because I generally look for labels on a sign pointing left, to be on the left-hand side of the sign itself! Whereas in #2, the bravo directive pointing left, while sitting to the right of the alpha designation, seems sort of backwards to me.

 

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2.

 

 

In this classic 4 way intersection, this really gets to the heart of my main question above in Question #1. Choice #1 here favors justified left location designator alpha with direction designator bravo being placed afterward, and both the left and the right arrow sharing the same letter—since I presume it would be awfully silly to label the bravo designator double-B

(" "),

just so that each arrow can have its own letter! Whereas choice #2 places the current location alpha in the center, with each directional bravo on either side with their own arrows respectively.

 

In this case choice #2 seems more intuitively correct as the letter placement on the sign physically mimics how the taxiways appear in the diagram, but is it wrong? Is choice #1 the only true, proper choice? Or is either correct? Or does it depend on what part of the world one is in?

 

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3.

 

 

Now let's ramp things up and make it a bit more complex. The pilot is still moving north on taxiway alpha, and approaching an intersection with taxiway bravo that keeps the same name both to the right and left of the intersection. However... the current taxiway the pilot is on (alpha), now changes names to charlie after crossing bravo. This now pertains to Question #2 at the top of my post:

 

I'll just ask quick and right off the bat, out of these 8 choices, is there any ONE that stands out as being not just the "most likely" correct, but the "absolutely beyond a shadow of a doubt" only correct choice? Or is this a complex example with a lot of gray area where more than one answer might be correct?

 

First off, this repeats the first question I had about the position of location designator and whether it's always justified left or center... so whatever the answer was to that, it will negate either the choices 1 & 2 or 3 & 4. But moving beyond that question, the next two questions I have pertain specifically to the position of and the arrow placement of the charlie designator.

 

In the case of Choices #1 vs. 2 (where the location designator is justified left), should the charlie designator always be listed first since it's the one most closely related to the one the pilot is actually on at the current moment (i.e.—alpha is changing names to charlie after passing through the intersection—as indicated in Choices #1a & 2a)? Or should the bravo designator be listed first, since the pilot will be passing through the intersection with bravo, before continuing onto the taxiway charlie (as indicated in Choices #1b & 2b)?

 

In looking at Choices #1 vs. 2 (or 3 vs. 4), while considering taxiway charlie, straight ahead, with an up-arrow indicator, is it more correct to have the up arrow to the left or the right of the letter in the label? This is a tough choice, as it seemingly could be either way. Obviously all directions left (be it left-down, left-across, or left-up) should have the arrow to the left of the letter itself; and vice-versa for the directions right. But up (or straight ahead) is tough, as there is no system that allows the arrow to be placed ABOVE the letter on the taxi sign. So which is it?

 

Finally, in considering Choices #3a & 3b, vs. 4a & 4b; if justifying the location designator alpha in the center is the correct choice, should the charlie directive designator then be placed to the left of the centered alpha, or to the right? This again is a tough choice, as the bravo left & bravo right obviously is placed to the left and right of the location designator alpha, respectively. But charlie (being alpha's replacement straight on), really should be on top of alpha, not committed to either side. So again, much to consider here. If there is one right answer I'd be curious to know.

 

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4.

 

 

Now entering "The Ball of Confusion" ("...that's what the world is today...") and a rather complex 8-taxiway intersection that probably seldom occurs in real life; but it's for asking questions. This diagram now pertains to Question #3 at the top of my post:

 

If we assume that center justification of alpha (as discussed before) is the correct choice, then that only leaves Choice #1 as the correct layout. But if justification left of alpha is more correct, then how should the directional designations to the right be handled in this scenario?

 

In choice #2, each taxiway is getting its own separate designation with its own arrow in clockwise order from left to right. But it's taking up a lot of space—maybe more than it should. And it reads really dense, and I'd imagine that for a pilot who has to pick up information as he/she's taxiing quickly, this could be too hard to read.

 

In choice #3, each designator bravo, charlie, and delta is conveniently sharing opposing arrows (180° apart from each other), because all 8 taxiways happen to intersect at the same point, and none of them change names after passing through to the other side. It reads much cleaner than in choice #2. However, this would not be possible in choice #1, as "left-center-right" layout would create the inconsistencies of right arrows being assigned to the left side or vice-versa.

 

Also, compared to choice #2, choice #3 breaks the pattern of the clockwise sweep of arrows from left to right, and mixes up right facing with left facing in an alternating fashion. Something that maybe ought to be avoided? I don't know for sure.

 

Again I ask, which is probably the most correct, or is there one definitely correct and only way to do this?

 

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5.

 

 

This final diagram now pertains to Question #4 at the top of my post:

 

Same intersection layout as diagram #4 above, only now all the taxiways change names after crossing the intersection! The 8-way intersection from hell! I doubt this would occur in most airports, but for labeling purposes I have to create an exaggerated scenario just so I know how to handle the more moderate ones as well:

 

In this case the justified center location designator of Choice #1 would seem like the most logical in "pictorially" describing the geometric layout in a linear sign format. And the clockwise progression of the arrows is very pronounced. However, it is long & dense, and a pilot is hard pressed to make sense of it in under 3 seconds. This also creates the ambiguous scenario (like we saw in my earlier diagram), where taxiway echo (straight ahead), must split the difference between 3-left and 3-right with alpha dead center and nowhere for it to go that is centered—so does echo get placed left of alpha, or right?!!!

 

Choice #2 really offers the same layout as #1, the only difference being that since the location designator alpha sits off to the side justified left, and all the directional designators are free to line up on their own, now echo can take its rightful place in the true center, without being forced to one side or the other of alpha. However, it's still messy as heck and reads very dense. And once again does the arrow get placed to the left or the right of the 'E'?

 

Choice #3, while being very unconventional I'd imagine, certainly cleans things up a lot by allowing opposing taxiways to share opposing arrows side by side. But here's the problem: Unlike diagram #4 where each taxiway kept the same name after traveling through the intersection, these don't! So though it may be simpler to put two different letters right next to each other with their respective arrows on either side of the letter-pair, is it proper? Especially if we consider the fact that eventually we may have two-character taxiway designations (like A1, A2, or even double-letter designators like AA, BB, etc.)

 

Plus in choice #3, we've reintroduced the dilemma of where do we place echo? All the way to the right, as I have done in choice #3? Or all the way to the left next to location designation alpha? Or straight down the center bisecting charlie and golf—which breaks the pattern of the two letter pairs with arrows on either side—thereby defeating the whole purpose of this approach.

 

So which is most correct given all these scenarios, so I can try to maintain the same consistency when making my own airports?

 

Thank you,

 

-- John

The source I use to find out taxiway signage is the FAA. If you go to http://www.faa.gov and search for publication 150/5340-18F, it will have the answers you're looking for.

 

Here is a direct link if you so wish:

http://www.faa.gov/documentLibrary/media/advisory_circular/draft_150_5340_18f.pdf

Okay thank you much. That is pretty much what I was looking for, my internet searches earlier today had yielded similar things as images, or single page guides, but not a whole pdf manual with examples.

 

Though oddly enough, it still doesn't really sort out the question of the location designators and when they're justified left vs. center. In the examples of complex airports, I saw both scenarios, and some with directive signage (black on yellow), without any location (yellow on black) at all! Especially at intersections that T'ed off at a dead end and forced a left or right turn... which surprised me, because I always thought the yellow on black location designator always had to be listed no matter what.

 

I saw some `B [A] B\ (with upper-left B on one side, lower right B on the other, with location designator A in the middle-- if it was a diagonal intersection such as I described. Yet if it was a 90-degree standard intersection it was ALWAYS in

 

[A] format. Never format.

 

So to me this inconsistency is strange, but at least I have a guide to go by. Thanks.

When I searched for 'taxiway sign rules' I cam across a Jeppesen pdf that was a little more abbreviated than the FAA. Here is a link to a direct download, http://ww1.jeppesen.com/documents/aviation/business/ifr-paper-services/airport-signs.pdf .

Hi again Tvieno,

 

Thanks for your continued interest in trying to help. I opened this pdf and this displays quite an array of guides and examples crammed into 18 pages! A good resource, but on pg.2, it further illustrates the confusion and ambiguity I'm having:

 

 

Both the choices I circled are the crux of my original question... regarding whether location designators (the yellow on black) should ultimately be justified left or center? And should one standard be adopted in all situations at the same airport, or is there *TRULY* only one situation where you use one and NOT the other?

 

My point is that despite all the guides you've directed me to, not one of them clears up this ambiguity once and for all. They don't even explain why one is used vs. the other, or that they are in essence the same thing, but their presentations are different. They simply list them and make it a point to explain the differentiation between a location sign vs. a direction sign... but not the layout itself.

 

I know this is probably not anything you can personally help me with. I just can't believe that there isn't one standard that everyone can agree on in this instance.

I think that is just it, there is no standard but just guidelines like the vs . I guess as long as you're consistent in the airport you're working on is all that matters

As tvieno said, it's all about consistency. From what I've seen when flying, though, the current taxiway is justified to the left when the taxiway sign is to the left of the taxiway. If it's to the right, then the current taxiway is justified right.

 

It's a guideline because there are always going to be exceptions. A sign may not be able to be placed to the left of the taxiway because of an obstruction, visibility issues, other structures (startup pads, holding pads, unusual configurations, etc). Generally, in my own view, it's the colors that matter the most and are more hard-coded as standard than the configuration. As long as I can identify red, yellow, yellow on black and white on black, pilots usually figure the rest out.

 

I will say, though that in tvieno's instance, cross-taxiway designators are usually separated in the U.S. only when there is a third taxiway at the intersection (i.e. ) or the cross taxiway is not completely straight (i.e.

 

If there's any signage indicating something in both directions other than a straight cross taxiway, usually the current taxiway is in the middle (choice #1). But you could have seen variances for many reasons, such as consistency of signage on a given taxiway, hot spots, known issues (FAA waivers, etc), and the like. In the case you gave about a T intersection, the current designator may have been removed for clarity's sake to orient the pilot or for some other reason.

 

Just my taxable $0.02.