If they want to get off the planet and don't, then yes, it's a Failure. But it can still be Failure/Good, and that "Good" doesn't have to apply solely to the MC. It can apply to everyone. Also, think about Dividends. You can make a failure story feel pretty "up" if that is what you, as the author, want to do.
If the characters, instead, have a Goal of Survival, and their first effort -- their first Option in the Optionlock -- is to get off the planet on the ship fails, this still leaves the story open for a Success ending. It really depends on how you set the Goal up.
Just to clarify a point about LOTF, only Ralph and Piggy think about getting off the island. As early as chapter three, Jack has to struggle to remember what "rescue" means. Also, it's Success/Bad just to drive home the idea that getting what one wants doesn't necessarily lead to a happy ending.
I don't have a big enough mental database to draw on, but I can't think of a story where the Outcome is determined really early. I feel like it must come after the Climax, or what's the point of the Climax? Even if the characters have a Goal (get off the planet) and then change the Goal (make the best of this)... you're not necessarily in need of a new story or storyform. Think of it again as an Option that doesn't work out. The author probably knows the OS Goal better than the characters in the story in this case.