A while ago.
The plane was supposed to crash, one way or another, and everyone on it was inevitably going to die.
The only person who wasn't supposed to die was Eleanor, whom Rudy had saved already. While he felt sad that he couldn't help the innocent victims on the plane, there was nothing he could do to stop that.
It was their fate to die. That was a situation, and it was challenging Rudy. Hence, Rudy took it personally and decided that he would change the fates. What could stop him from doing that?
That's what he wanted to know.
However, he still didn't have time to teleport each and every passenger out of place. Rudy was left with no options to try, and that's where he made his own option.
Situations like that were the best to come up with new abilities and try them. Sure, the risk was there, but it was better than not trying.