# Are taxiways numbered in a predictable order?

When taxiing at an airport without a full-blown airport diagram (most commonly, a non-towered airport), how does a pilot know whether taxiway A (Alpha) is on one end of a runway, or the other? Or, in the case of taxiway exits, how does one know whether exit A1 is at one end of a runway, or the other?

In other words, are taxiways numbered in a predictable or consistent way? An example would be, “Exit A1 is always located at the easternmost exitway of Alpha”. If they are, is this because of custom or regulation?

In the U.S., taxiway number/nomenclature is generally designed in accordance with FAA AC 150/5340-18F. Also, Engineering Brief 89 available here clarifies some of the information in the AC with respect to taxiway numbering/nomenclature. The two pages shown below summarize the guidelines for numbering (from Engineering Brief 89)

Also, note the general taxiway numbering/nomenclature schema for Los Angeles International Airport (KLAX) illustrated on the bottom of this page. The letter "A" starts the taxiway nomenclature beginning on the south side of the airport and progresses alphabetically towards the northside of the airport. Intersecting taxiways are numbered sequentially.

Airport taxiway nomenclature can be very complex depending on the airport. Also, as modifications are made to the ramps and movement areas, etc., effectively designating taxi routes or other areas of the airport becomes challenging.

Finally, in the U.S., there is a taxiway numbering/nomenclature methodology that is framed within FAA guidance documents. A close comparison of the design guidance with current airport layouts and taxiway numbering/nomenclature not only illustrates the complexity involved but also reveals, in most cases, a consistency that can be relied upon and proves to be extremely useful in actual practice.

Excerpt from Engineering Brief 89 (two pages):

• So, while there is a very definite and logical scheme to naming taxiways at an airport, there is no consistent scheme across all airports as asked in the OP. i.e. Taxiway A is not always the eastern-/southern-most taxiway with Z being the western-/northern-most (or something similar). Nov 16, 2018 at 20:41
• @757toga The problem is the standards don't really help. We know there will be some form of logic, but even your highlighted bit demonstrates that each airport authority can choose a different starting point. If A is North-West in one Airport, and South-East at another then that's not really useful for our purposes - and even that method isn't mandatory. And while OP didn't say All, the crux of the question is looking for something that can apply at all airports
– Dan
Nov 17, 2018 at 8:07
• @757toga You seem to have a very odd take. The question is 'Are taxiways numbered in a predictable order?' and the answer is "No". You have absolutely no way of landing at any random airport in the world and taking even a guess at the taxiways. My answer also isn't US Centric and using two international airports by way of example is not "anecdotal". I didn't say there was no thought - I said an outsider couldn't accurately predict it
– Dan
Nov 17, 2018 at 15:05
• Of course, even that standard isn't universal. Some two-letter taxiways at KIAH, KDFW, KDEN, and KATL use N/S/E/W prefixes for other letters. Those are sprawling airports that are in some ways designed as multiple fields with distinct taxiway systems and only loose connections between them, e.g. Twy EC would be somewhere in the East airfield and Twy WC would be somewhere in the West airfield. Nov 17, 2018 at 17:51

Not at all - they'll be built-up in a logical fashion in so much as they're not just randomly assigned but there's no standard beyond the use of letters to denote taxiways and numbers to denote holds. Each airport is free to "make up" it's pattern of taxiways and exits as it sees fit, and many will evolve and grow over time.

For example, at Birmingham International taxiway A (Alpha) takes you from the runway to an intersection with T (Tango) and D (Delta). Bravo is a small spur between the runway and Alpha and there is no Charlie.

At the other end of the runway is Echo and Sierra.

At London Gatwick, Alpha isn't even used on 26/08 - rather it's Juliet, Quebec Hotel and Golf. And neither runway has Echo or Sierra.

In short, there's no substitute for simply knowing (Through the use of chart or local knowledge), looking for signs for asking for a progressive taxi where the controller gives you step by step instructions.

• Evolving is a good point. There may have been some logical plan when the airport was first built, but reconstruction over the decades may have rendered it almost unrecognizeable. Nov 17, 2018 at 18:03