The most common and most likely answer to this crossword clue is the 9 plus 4 letter word MILE-HIGH CLUB
I've seen this crossword clue in The Guardian
M
I
L
E
-
H
I
G
H
C
L
U
B
Buddy explains!
The straight part
We know that "Taking to the air, its members are bonkers" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case taking to the air, its members are bonkers = mile-high club.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.