This will help you out: http://www.moddb.com/mods/survivalcompaign/videos/walkthrough-predator-level-1-spoiler-alert
i think i know what your talking about, if you got your sound turned up, you will hear the ladder volumes connecting to help you get up. use the edge of the ledge with simple jump near the hole!
And for the next part, don't continue using crouch key cause in ladder volumes that restricts your movement, i think its a crouch jump and let the ladder volume do the rest.
After testing it seemed to be to hard for casual gamers to make it without the ladder volume.
The Pred "high" jump technique is a bit of a skill to figure out. Most casual gamers don't know how to crouch then jump and maintain crouching to get up onto really high ledges.
That's the reason i set it up like this.
yeah i know about the queen. she would get stuck in between the terrain and key framed apc crashing the game or getting stuck on terrain ceiling and quitting the chase, simply put the roof is set to non solid to avoid this. the Ai do the most ridiculous things when you leave it up to them!
where did you need to jump with the marine?