The most common and most likely answer to this crossword clue is the 9 letter word SAILPLANE
I've seen this crossword clue in The Guardian
S
A
I
L
P
L
A
N
E
More clues leading to the result SAILPLANE
Buddy explains!
The straight part
We know that "Aircraft/Aircraft" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case aircraft/aircraft = sailplane.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 SAILPLANE mean?
SAILPLANE noun- A glider that is optimised for soaring and is equipped with fixed wings and fuselage.
- To fly in a sailplane.