Round 1: Wait on top and kill all but one guy, then use a ultimate to push into the pit
Round 2-15: CC the rushers incoming to the pit and then slowly eliminate target after target
For the bombing runs: decide on one especially tanky guy to do the run, supporting him by activating an ultimate or EMP-grenading the turrets.
For the last round: you only need to clear out one side of the room, on which your tanky guy can push for the final plant and there you go, you just got yourself a nice 240 GS piece of equipment :-)
The Division - Falcon Lost Incursion Guide
The Division - Falcon Lost Challenge Mode - Under 20 Minutes - No Exploit/Glitch/Bug
The Division Falcon Lost Incursion Challenge Mode Complete (XB1) 1 hour 17 minutes long