Still with software science translations.. Now I'm coming to you with this expression that have always bothered me: "on the fly"

How the hood would you translate that elegantly to spanish?

It feels like "sobre la marcha" is way overkill, at least from a structure point of view. Also "al toque", sounds maybe too coloquial.

What do you think?

edit: so the english sentence could be:

The value is returned from a new function executed on the fly.

  • Could you please show the exact sentence you want to translate?
    – qPCR4vir
    Apr 26, 2013 at 9:08
  • Yes, an example would help. Apr 26, 2013 at 11:56
  • I'll try to upload something tonight, this is a precise example I have from a given software that I don't have right now.
    – Sebas
    Apr 26, 2013 at 20:26

4 Answers 4


No, I don’t like very much sobre la marcha. I mean, not always, and in “software science translations” almost never. I don’t feel it translate the whole idea exactly, with sometimes is: immediately and automatically, without user’s or external elements intervention.

There are many other possibilities.

My favorite is the simple direct translation: “al vuelo”.

Let’s see what the RAE said about “vuelo”:

al ~, o a ~.

  1. locs. advs. Con prontitud.

cazarlas alguien al ~.

  1. loc. verb. Entender o notar con prontitud las cosas que no se dicen claramente o que se hacen ocultamente.

coger al ~ algo.

  1. loc. verb. Lograrlo de paso o casualmente.

cogerlas alguien al ~.

  1. loc. verb. coloq. cazarlas al vuelo.

alzar el ~.

  1. loc. verb. Echar a volar.

  2. loc. verb. coloq. Marcharse de repente.

I like this more than “sobre la marcha”, with the bonus that many people will automatically translate it to on the fly with the exact original meaning.

Some of the other possibilities are:

“sobre la marcha” (of course),



dinámicamente (this is probably my second favorite). The windows layout change on the fly. El diseno de la pantalla cambia dinámicamente. (a sort of this)


Let’s see some concrete examples:

I have a class which calculates it's property on-the-fly, for example:

Tengo una clase que calcula sus propiedades al vuelo. (dinámicamente, en tiempo real)(I’m not sure how to correctly translate class and properties)

An example enlightens the kerning-on-the-fly functionality:

Un ejemplo aclara esta funcionalidad de posicionamiento al vuelo. (dinámico, instantaneo, sobre la marcha)

Encryption on the fly. Cifrado al vuelo. Cifrado simultaneo, en tiempo real, dinámico, automático…

On the fly translation. Traduccion simultanuea. (al vuelo, instantanea, sobre la marcha)

More examples are here.

  • wow, great, that's why context matters!
    – Sebas
    Apr 26, 2013 at 11:47
  • That's the kind of translation I'm afraid of, since it is really litteral from "on the fly". But apparently it still works sometimes :-)
    – Sebas
    Apr 26, 2013 at 11:48
  • 1
    Well... I work in a software company, and never heard "al vuelo". Still sounds to me like Latin American expression, like "al tiro" or "al toque". I'm agree with "simutáneamente" or "dinámicamente", but all the examples you give with "al vuelo" sound very weird to me... Regardless RAE says, we don't use that expression.
    – Arkana
    Apr 26, 2013 at 11:53

I would generally use sobre la marcha and I don't see it as overkill.

What does this phrase have to do with Scientific translations? Maybe a few examples would help.

  • 1
    in computer science this is a very common term. thanks for your input.
    – Sebas
    Apr 25, 2013 at 11:52
  • "on the fly" is used in ordinary discourse. Does it carry an extra meaning when used in technical prose? An example would help. Apr 26, 2013 at 11:54
  • Walter, in french (and I think spanish as well) this is not (so) ordinary.
    – Sebas
    Apr 26, 2013 at 12:06
  • "On the fly" is used in ordinary discourse in English. I have probably seen it in computer oriented literature, but I never noticed any particular meaning to it, beyond its ordinary meaning. Again, an example in your original question would help clarify what you are looking for. Apr 26, 2013 at 19:45

"Al toque" sounds to me like Latin America spanish... in Spain, al least in Madrid, we don't use that expression.

"On the fly" can be translated in several forms, but "sobre la marcha" I think is the most accurate. Other forms can be "al momento", "instantáneo" or "conforme se vea". Depends from context, but I think "sobre la marcha" is the most elegant, formal and easy.

Some examples:

We will fix the errors on the fly. - Iremos corrigiendo los errores sobre la marcha / conforme los veamos.

The system enables 'on-the-fly' processing of queries. - El sistema permite el procesamiento instantáneo de consultas.

  • thank you, the example made it clear. Also, I worked in buenos aires and madrid that's probably why I'm using a blend of expressions :-)
    – Sebas
    Apr 25, 2013 at 15:29
  • 1
    I've never heard "al toque" being used in Mexico, FWIW. "Sobre la marcha" is the most common.
    – Roflo
    Apr 26, 2013 at 0:08
  • @Roflo Gracias por la aclaración :) Me sonaba a expresión latina, como la expresión chilena "al tiro" (no sé si ésta última se usa también en otros países). Aunque, como dice user2166141 es cierto que me sonaba más a "immediately after".
    – Arkana
    Apr 26, 2013 at 6:24
  • El sistema permite el procesamiento inmediato de consultas. Apr 26, 2013 at 12:00
  • @WalterMitty Yes, that can be another, like (as I said) "al momento", or "instantáneo". Thery're act as synonyms in this context.
    – Arkana
    Apr 26, 2013 at 12:07

I'm from Latin America and "al toque" doesn't mean exactly "on the fly", the correct translation would be "sobre la marcha".

"Al toque" it's more like a "immediately after".


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