In non-aviation world, separation between letters in acronyms is either nothing (e.g. URL) or a point (e.g. A.M.). But in the aviation world, the "/" is common (e.g. G/S, V/S).

I'm puzzled as:

  • some acronyms never use "/" (e.g. ATC)
  • some acronyms almost always use the "/" (e.g. V/S")
  • some abbreviation use this separator but are not acronyms (e.g. A/THR, THR containing more than one letter)

Why is this separator so spread in this worlds ? Why some acronyms does not use this separator ?

  • 1
    $\begingroup$ I think it is not only common in the world of aviation but in the English language in general. Think of "a/c" for aircraft and "a/c" for air conditioning. But indeed, I find this funny as well. $\endgroup$
    – PerlDuck
    Commented Sep 1, 2019 at 7:26
  • $\begingroup$ @PerlDuck I'm not a native english speaker, that may be why I find that weird :) . Yet, I'm still puzzled (as explained in the question). $\endgroup$
    – Manu H
    Commented Sep 1, 2019 at 8:50
  • 1
    $\begingroup$ I think it’s useful as a separator in abbreviations (e.g. for A/THR you immediately see which group of letters stand for which original word) so it helps as a visual indication of what it is you’re reading. The dot would double as a separator of sentences and inside abbreviations, and since uniqueness of symbology is always a good idea, the slash helps there, too. Can’t say that’s the reason, but at least that’s why I like it. $\endgroup$ Commented Sep 1, 2019 at 9:11

1 Answer 1


It's not just aviation, it's standard in English.

The slash has become standard in several abbreviations. Generally, it is used to mark two-letter initialisms such as A/C (short for "air conditioner"), w/o ("without"), b/w ("black and white" or, less often, "between"), w/e ("whatever" or, less often, "weekend" or "week ending"), i/o ("input/output"), r/w ("read/write"), and n/a ("not applicable"). Other initialisms employing the slash include w/ ("with") and w/r/t ("with regard to"). Such slashed abbreviations are somewhat more common in British English and were more common around the Second World War (as with "S/E" to mean "single-engined"). The abbreviation 24/7 (denoting 24 hours a day, 7 days a week) describes a business that is always open or unceasing activity.

(Slash (punctuation) § Abbreviation, Wikipedia)

Note that there is a difference between abbreviation and acronym, though that line in recent usage is blurred.

Boeing uses VS for the 777, and V/S for the 737. Language is more about what's more common, preferred style, and/or trends (e-mail becoming email). For example, knowing when to use a hyphen, space, or no-space, for compound words requires checking a dictionary. There aren't fixed unchanging rules to follow really in language.

There are some questions on the topic on English Language & Usage Stack Exchange.

  • $\begingroup$ I'm still puzzled as there is no separator in ATC or PA (public address) $\endgroup$
    – Manu H
    Commented Sep 1, 2019 at 10:19
  • $\begingroup$ @ManuH: see update. $\endgroup$
    – user14897
    Commented Sep 1, 2019 at 10:42

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