[Grammar] Present Continuous for planned action + condition

Dear colleagues,

I need your help in explanation of the next issue:
I explained the rule about using the future tense in case, when we speak about future action and have subordinate clause with condition. So the main action we express with Future Indefinite and condition part – with Present Indefinite (for example, If the weather is fine, we’ll go for a walk). But my student asked me, what if the main part is a planned action and we studied that we can use Present Continuous in such case? Can we say, for example, “I’m flying to Paris, if I buy tickets”? Is it possible? Or should we say “I will fly to Paris, if I buy tickets”?
Please, help me with this challenge)

I think if you say "I am flying to Paris (next Saturday)" you're implying you've bought tickets already. That really sounds like an arrangement to me. So there are no grounds for a condition.

Manya Vtumane said:

Dear colleagues,

I need your help in explanation of the next issue:
I explained the rule about using the future tense in case, when we speak about future action and have subordinate clause with condition. So the main action we express with Future Indefinite and condition part – with Present Indefinite (for example, If the weather is fine, we’ll go for a walk). But my student asked me, what if the main part is a planned action and we studied that we can use Present Continuous in such case? Can we say, for example, “I’m flying to Paris, if I buy tickets”? Is it possible? Or should we say “I will fly to Paris, if I buy tickets”?
Please, help me with this challenge)

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Manya Vtumane said:

Can we say, for example, “I’m flying to Paris, if I buy tickets”? Is it possible? Or should we say “I will fly to Paris, if I buy tickets”?
Please, help me with this challenge)

Click to expand...

Neither of those sentences make much sense. We don't decide to fly somewhere depending on whether we've bought tickets or not. We decide to buy tickets depending on whether we want to fly somewhere.

Your student's question is also unclear. "

Thank you very much for the answers!
But I need to make some clarifications.
My example was not very proper, sorry.
This can make the issue more clear: “I bought the tickets to fly to Paris. I’m flying tomorrow, if everything is fine with the plane”. So here is the planned action and condition.
And we have two rules about future tense: on one side 1) Present Indefinite is for spontaneous actions and Present Continuous is for planned actions. And on another side 2) when we have two actions in the future: one is the main action, and second is a condition, we use Present indefinite for condition and Future Indefinite for the main action. So my student couldn’t understand the difference, because the main part of the sentence was the planned action. Logically, we have to use Present Continuous here.
Is it so that we use Future Indefinite in this case because the condition influences the main action and the result will be spontaneous anyway? I mean the result will be spontaneous anyway, depending on conditions, not on your plans.

Manya Vtumane said:

“I bought the tickets to fly to Paris. I’m flying tomorrow, if everything is fine with the plane”. So here is the planned action and condition.

2) When we have two actions in the future, one being the main action and the second being a condition, we use the Simple Present [Present indefinite] for the conditional clause and the Simple Future (or 'will') [Future Indefinite] for the main clause.

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I've amended your question to see if my understanding is the same as yours.
We can start with the (correct) premise that the following sentence is correct English:
"I’m flying tomorrow, if everything is fine with the plane”.
Your rule 2) above indicates that the first clause should be in the Future Indefinite ('will fly').
It's not.
Therefore, rule 2) is wrong. We do not do this.

I also question this:
"Logically, we have to use Present Continuous here"
No. Logically, we can say, "I will fly tomorrow, if everything is fine with the plane” or "I fly tomorrow, if everything is fine with the plane”.
Perhaps the original would be more common, but all of these three forms work.

PS: Thinking about it more, I can see the reason for this "rule". It's certainly true that if you are negotiating with someone, you would say, "I will do this, if you do that." But that is only one context in which we can have two clauses in the future with one being a conditional. The flying example is another context, and doesn't require "will". Many contexts don't fit this rule.