Why do they repel down instead of landing the helicopter? Too much sand/dirt?
It's probably cos this is a demo for some vip or PR purpose. Plenty of examples in the ME of choppers stirring up a storm.
Repel is quicker by something like 15-20 seconds in peace time, those are some of the most dangerous moments for a helicopter so reducing those moments are a very good thing.
In peace time after the passengers get down their will have to reel in the rope. In war times the ropes would be cut so it would be even quicker on top of that.
A rappel is slower than a straight out egress through the doors.
If LZ is suitable, chopper lands, everyone debusses.
If not, chopper hovers at 6 feet, you throw the heavy stuff out and jump down.
If LZ is tight (not enough clearance), you rope in.
A heli-rappel, where you slide down the rope on a mechanical descender is the slowest method. Operationally, you need one rope per trooper. Peace time, we don't reel the rope in, the rope is attached to a quick release and once everyone is off rope, crew chief simply pulls the QR and drops the ropes.
Alternate method, used more often, is fast rope where you slide down a much thicker rope using your body and boots, instead of a descender, for friction to slow you down. Fast rope is much faster than rappel (but rappel is rated for much higher insertions) and can get multiple troopers on a single rope (unlike rappel).
Example of when we'd use fast rope - probably MOUT is most common cos you need to get troops in but the chopper can't get to within 5-10m of street level cos of buildings, trees, telephone poles,e tc.
Example of when we'd use heli-rappel - in the jungle when you can't cut a LZ big enough for the chopper to land, you can rappel in from how ever many meters the canopy level is. 30m to 40m is easy on a rappel even with a full combat load. You wouldn't fast rope that kinda of height
In the pics above, you've got guys fast roping out the side doors and other guys rappeling off the tail ramp.
