Using the future tense

[Billy Bosworth]

This is the sentence to be translated: They will ring when they get there. 

I am aware of a "rule" (?) which states that in the case of 2 future tenses/actions, the French has to make a distinction between them and show that one action has to be completed before the other. 

In this case, they have to perform the action of "getting there" before they can perform the action of "ringing".  This means that you can't simply put them both in the future, as there would be no distinction.

So the following would NOT be acceptable: Ils appelleront quand ils arriveront .

The correct translation would have to be: Ils appelleront quand ils seront arrivés. 

I would appreciate your views, as both of my sources claim to be correct :-). 

[George Hunt]

Am vaguely aware of this use of the future tense,but not well enough to know the  "rules"

I would agree that your second translation is better.

I also thing that you could just use the present tense for "arriver".

No doubt Chantal will have a proper explanation.

[Chantal Savignat]

Hi and first

Je souhaite une bonne année  à tous ceux qui liront ce message.

Meilleurs voeux de bonheur pour 2020.

These "rules" are called "concordance des temps".

We have 2 tenses : futur simple and futur antérieur.

In a sentence with 2 actions in the future. the verb used to say the first action before a second action (the second action is written in "futur simple") is written in "futur antérieur"

About

Ils appelleront quand ils arriveront  / Ils appelleront quand ils seront arrivés. 

The second sentence respects the rules.

But both sentences are commonly used. Maybe with another verb it would be wrong but with "arriver" it's correct. I think the first way is more used than the second.

The only thing is that this  is not exactly the same meaning but very very closed.

Ils appelleront quand ils arriveront = they will ring exactly when they will arrive at home = they open the door, they put down their coat  and they ring. The two actions are described at the same time.

Ils appelleront quand ils seront arrivés = insists on the point that they will ring only when they will be at home and not before. the 2 actions are described as one after another.