'will be V-ing' vs. the present progressive [for future reading]

iii When the meeting ends we’ll be flying to Bonn.

This doesn't strictly specify that "we're the ones who participate in the meeting". That would be the most sensible explanation for why the sentence includes these two clauses, but the sentence could be logically true even if the meeting has nothing to do with us. The dependent clause "When the meeting ends" doesn't actually contain any element that is grammatically connected to the word "we" in the independent clause.

Sentence iii does mean, more or less, that "we're scheduled to fly to Bonn right after the meeting ends". I wouldn't necessarily use the word "scheduled", because that seems to suggest that there has to be a formal or communicated plan: in fact, I think the sentence could just as well refer to an informal plan. I would say that "we'll be flying to Bonn" in this sense is synonymous with "we're going to fly to Bonn".

(1) When the meeting ends we’re flying to Bonn.

It is not strictly impossible for this sentence to have the aspectual (progressive) meaning of "be _ing", but that interpretation would be rare, because with an aspectual reading, there aren't many circumstances where the present tense is appropriate. The best frame I can come up with is a "historic present" or a present-tense narrative, like this:

They call me while I'm getting on the plane to tell me that the meeting is starting. When the meeting ends we’re flying to Bonn.

It feels weird, but actually, even iii seems awkward to me in the "aspectual" interpretation, because it's hard to imagine how someone could already be in the process of flying somewhere right at the end of a meeting. I had to imagine that the meeting is going on somewhere else, and so the people who are flying on the plane just hear about it on the phone.