The most common and most likely answer to this crossword clue is the 8 letter word STEPWISE
I've seen this crossword clue in The Guardian
S
T
E
P
W
I
S
E
More clues leading to the result STEPWISE
Buddy explains!

The straight part
We know that "in flight?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in flight? = stepwise.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.
What does STEPWISE mean?
STEPWISE adjective- One (small) step or stage at a time; gradual; piecemeal
- One step or stage at a time; step by step