The most common and most likely answer to this crossword clue is the 5 letter word SOLOS
S
O
L
O
S
Buddy explains!

The straight part
We know that "flights" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case flights = solos.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 SOLOS mean?
SOLOS noun- A piece of music for one performer.
- A job or performance done by one person alone.
- (games) A card game similar to whist in which each player plays against the others in turn without a partner
- A single shot of espresso.
- An instance of soloing the football.