The Cambridge Grammar of the English Language (Page 171-2):
 i When we get there, they’ll probably still be having lunch. [aspectual meaning]
ii Will you be going to the shops this afternoon? [special meaning]
iii When the meeting ends we’ll be flying to Bonn. [ambiguous]
(Discussion of [22i] and [22ii] omitted.)
The distinctness between the two meanings is seen clearly in the ambiguity of [22iii]. On the progressive aspectuality reading, we will already be flying to Bonn when the meeting ends; on the ‘already decided future’ interpretation, the when adjunct says when we will leave. The first is imperfective, with reference to a mid-interval; the second is perfective, just as in the non-progressive we’ll fly, which, however, suggests that the decision is being made now. This use is particularly common with will, but it is also found with, for example, the idiom be going, as in Are you going to be helping them again this year? (where the non-progressive might again be construed as a request).
In the special meaning (aka, the ‘already decided future’ interpretation), [22iii] seems to mean that we're the ones who participate in the meeting, and that we're scheduled to fly to Bonn right after the meeting ends.
Am I right?
Also, what if will be flying was replaced with are flying?
(1) When the meeting ends we’re flying to Bonn.
Can (1) have both the aspectual meaning and the special meaning? Or can (1) have only the special meaning?