The operations depicted are not uncommon on construction sites (e.g. when mounting rooftop equipment) and there are OSHA regulations for helicopter cranes. https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=...
You need to see it in HD to see the rope. It's called "recovery assisted landing" or sometimes "hauldown".
Ski lift installations are rare, but power line towers go up by the tens of thousands. So the power line people need a way to do this routinely and safely.
1. Tower segment is hanging from helicopter.
2. Tower segment is in place with pins preventing it from falling over, but can be lifted away by the helicopter.
3. Tower segment is in place with pins preventing it from falling over, and will be released if the helicopter needs to fly away.
4. Tower segment is in place, fully secured by bolts.
The key point here is that under good conditions -- and they only ever do this under good conditions! -- a few pins is all it takes to stop the tower segment from falling over, but they won't stop the helicopter from lifting it off again. Securing the tower with two dozen bolts is only necessary when you want it to stay in place during strong winds and with the added load of the lift cable + chairs.
This is due to the calculated risk of something going wrong: workers on the pole can quickly move around if the unmounted pole starts falling, similar to lumbar can quickly change position when tree falls. With helicopter however, a violent pull of attached line could probably end up with part of helicopter being chunked out of the hull.
Deck hand on Indian fishing trawler is more toward the dangerous end. This is pretty in the middle. Very few variables are uncontrolled here. Anything involving confined spaces and chemicals is definitely more on the dangerous end.
In the event there is a risk to the helicopter due to the winch operation (such as the line becoming stuck in some tress below) - the pilot has the ability to cut the cable to ensure the helicopter is not compromised.
http://www.raf.mod.uk/rafsearchandrescue/rafcms/mediafiles/7...
The use of guide cables/pins was really neat. Assuming the camera is 'real' time (it wasn't sped up for the video) it looks like about 15 seconds between starting to pull the guide cables through to the point where they have two bolts installed. So a pretty narrow window for problems, of course you wouldn't do it when it was windy out either.
It seems that there are reasonably long period of time here when the helicopter is still connected to a tower segment when the workers are in the process of screwing bolts in. Why isn't this problematic?