The most common and most likely answer to this crossword clue is the 2 plus 7 letter word ON ARRIVAL
I've seen this crossword clue in Financial Times
O
N
A
R
R
I
V
A
L
Buddy explains!
The straight part
We know that "after the plane has landed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case after the plane has landed = on arrival.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.