David Russi Feb 6, 2009:

You're wanting to apply a rule to every possible instance in a case where clearly you cannot. Every language has rules that inevitably fail in certain situations, and for every rule grammarians give you about the use of por/para you will find exceptions. Why? Because language is spoken by people, and sometimes things are not said a certain way for a variety of reasons, including the best one: they just don't sound right...

Edward Tully Feb 6, 2009:

I think this is why it has fallen out of use, because of the similarity to "por" - "para" means that the subject has everything in order, prepared, etc., which almost always has the same meaning as "por", "is about to" - I really wouldn't worry too much about this!

Non-ProZ.com (asker) Feb 6, 2009:

ATERRIZAR It seems clear, according to most of you, that "El avión está para aterrizar" is not what native speakers of the Spanish language would normally use. But then, what do you think of las siguientes explicaciones del Diccionario de Uso de Español de M.M. sobre ESTAR PARA
María Moliner :**Ser *inminente que el sujeto haga lo que expresa el verbo que sigue: ‘Mi hermano está para llegar de un momento a otro’. o Estar a punto de, Estar al.
María Moliner :
**Inminencia de la acción expresada por el verbo afectada por «para»: ‘Estamos para marchar de un momento a otro. La fortaleza estaba para rendirse’.
Otro ejemplo encontrado en un libro de didáctica : El bote está para zarpar.

Me quedo perplejo.

Non-ProZ.com (asker) Feb 4, 2009:

ATERRIZAR Dicen que "El avión está para aterrizar" no se utiliza.
De acuerdo posiblemente, pero porqué se encuentra:
"El tren está para salir"
?

Parrot Feb 4, 2009:

This might be more a question about the use of "por" and "para". As David mentions, "El avión está por aterrizar" means "about to land", whereas the second sentence is not likely to be found. Random Google search gives the parallel example "Lance (Armstrong) está para ganar el tour". Lance is predisposed (determined?) to win. We normally don't say the plane is determined to land... the pilot, maybe.