As BH9 says, its Suspended Extraction....however what they are doing is madness. Why so high?
Suspended Extraction is more or less and emergency situation and only designed to move the troops the absolute minimum distance, so that you can put them down, land to pick them up and get away quickly.
SE is not fun to fly. You fly slow and are very limited in your ability to manoeuvre.
(exactly like long-line work but with someone shooting at you).