Well it was bound to happen. Putting one wrong number in by mistake. How many times has it happened before 9/11 and been corrected with a call from atc and an apology from the crew.
No need to lynch the crew guys, it could happen to anyone if they're tired or distracted.
Maybe a time to review the software to require double entry of the hijack code.
Whoever the crew was i'm feeling for you guys. Hope Virgin see it for what it is.