I came across this phrase in another SE question here: What's the meaning of the Mexican expression “se te va el avión”?
While I understand the idiomatic reference the phrase makes, I don't understand the grammar used. Literal meaning being "the flight/plane leaves you," shouldn't we be using dejar instead of ir? Also, what's the purpose of using two objects here? Shouldn't te alone be sufficient since it's already implied that it's the plane that's leaving?
Regarding the two objects, I think is a case of "dativo superfluo", which some people think are not really indirect objects, but an "objeto of interés"
Indica el interés de la acción, es decir, no es el destinatario sin más (Complemento Indirecto), sino el afectado por la acción.
Las expresiones con se me / se te / se nos / se os implican que el suceso queda fuera del control de la persona y que ésta se ve afectada por ello
Meaning that the object is there not really to tell you who suffers the action, but to stress who is affected by the action instead. It seems that there are several different kinds of dativos regarding not only who suffers the action but the action suffered (please, check the link for more exhaustive information).
So in Se te va el avión the event of the plane leaving affects the person addressed by this sentence. Compare
Se va el avión
which has a meaning like The plane is leaving with
Se te va el avión
which means "Your plane is leaving", you better hurry up, because there are consequences for you. You are going to be directly affected by this event
That is why we have two objects there that seem redundant, one is pointing who suffers the consequences of the action.
About the differences between dejar and ir, think about this: The plane is leaving, leaving you behind.... The first leaving would be from Ir since the plane goes from here to somewhere. Dejar, when talking about traveling, has the connotation of "dejar atrás". You could say
El avión deja Madrid (para dirigirse a Barcelona)
El avión deja la pista y sube hacia al cielo.
I understand your confusion, because the plane is actually leaving behind the person you are addressing, but then you would be saying
El avión te deja en tierra (the plane leaves you behind)
Or to phrase it with the words of the example:
A las 3:30 se cierran las puertas y si no estás dentro, se te deja en tierra (you are left behind)
So, as you can see, with dejar you will need a complement for that verb. Also is obvious that you suffered the consequences of the action, so there is no need of the "se te" construction to indicate it. In El avión te deja en tierra you are de CD of the action done by the plane. If you use The plane leaves you may (or may not) use the construction to indicate the consequences.
irse means go away, leave (dejar) or depart depending on context. So that se is turning the ir meaning into dejar, as you think it should be. You could read the sentence of the question as el avión se va sin ti or el avión te deja (atrás).
The pronoun "se" has many functions and is unlikely to learn them. Native speakers simply use it without conscience, nobody knows what it means. Usually gets a pronoun instead of the third person, with sintactic function of object:
Presté un libro a María.
Se lo presté. (se = "a María", indirect object) (lo = "un libro", direct object)
In "Se te va el avión" the word has no "meaning", is not a third person, neither an object. Has a syntactic function called "inchoative" that indicates the beginning of the action:
El avión se va = the plane started "going" action.
The "te" pronoun in this case is like an indirect object, which is indicating that the affected by the action of the verb is the second person, the receiver of the message.
El avión se te va = you're the one affected by the plane is leaving
Imagine it like this:
Se te fue el avión.
You have a plane. It is yours and you have it on your hand, but the plane flies away. Its gone "se te fue". The plane is what you think, the ideas so when the plane flies away, flies with your ideas, the plane is your toughts and they're gone.
