General Discussion

Trump didn't seem to understand why the helicopter couldn't get out of the way. He was talking as if the pilot saw the jet, had plenty of time to maneuver, and instead thought something along the lines of, "Gee, there's a plane, well, I guess I could stop, or go up or down or left or right...duh, guess I'll just crash into it."

He seemed utterly confused about this, talking as if there was no way the pilot couldn't have seen the jet coming, as if they practically crashed into the jet on purpose. That's why he was saying, "You can stop a helicopter very quickly. They can go up or down." He wasn't trying to make some kind of smart comment about helicopters. He was just trying to sound authoritative about something he only has a vague concept of, as usual. Like, if he was flying the helicopter, he would have gotten out of the way.

Anyway, apologies if it was not clear from the OP -- I posted this as I was watching his press conference, so the context was apparent in the moment.

(I will add that even if the pilot had seen the jet at the last second, the Black Hawk was probably doing at least 150mph. You obviously can't just stop on a dime at that speed. And a Black Hawk isn't a small helicopter like the one in the video.)