Special Patrol Insertion/Extraction
I used to LOVE to do this hardcore shit.
It’s used when you want to drop a stick of Recon Marines into a heavily forested or jungle environment where you wouldn’t normally be able to set a helo down.
Its also used for water insertions and extractions. Although having the helo simply set down on top of the water and drop its ramp to allow the Marines to climb on or off is a tad easier — but much less fun.