Objective: Regroup at dock, Pilot the boat, Head up river to the crash site
At the start of the mission, before boarding the gunboat, look for the intel on top of the crates to the left of a burning drum.
Crash Site Intel 1/3
Board the boat and have full control of the navigation and weapons. Go along with your allies and destroy everything – marked targets, structures and all. Continue up river and destroy the marked targets. You'll eventually run into a much sturdier PT boat. Keep moving while firing at it to defeat it. Use the buildings for cover.
Objective: Investigate the crash site
After disembarking from the boat, check the ground along the path, near the shore for another intel.
Crash Site Intel 2/3
Fight your way through the path until you reach the crash site. Go up the plane's wings and jump down to the cabin. Look around on the ground to find the last piece of intel in this mission.
Crash Site Intel 3/3
Approach the marked crate and equip the China Lake. Peer through the ripped part of the cabin then shoot the hostiles below until the Hinds appear and ruin it all. Watch the following scenes.