You know, this industry never ceases to give me a chuckle.
Taken at face value, somebody attempted a job they hadn't done before, or had been trained to do - if there's anyone on here with any real utility category experience who claims to have never been put in that position, I call bull-****.
Moving on.
Tower construction can be difficult, but like almost everything we routinely do in helicopters, it CAN be done, and it CAN be done safely. Meaning, you only need to learn how, it's not voo-doo magic that only some of us get to use. Asking questions (albeit prior to the event) is a very large part of that learning curve.
Line length is individual preference. I set with anything from 50ft to 150ft depending on the job, the helicopter in use, the terrain, and the ground crew. How do I know which to use? Experience. The human eye isn't able to effectively discern depth beyond roughly 100ft, so in order to use a longer line effectively for precision work you need two things: experience on longer lines, and a bag of tricks to work around your inability to accurately judge depth - that comes with the experience.
Setting a tower on a small reference point can be intimidating, but you have to realize that setting it the top of the first piece requires nothing more than the skills required to set it on a 2ft by 2ft piece of wood lying on the ground, or any other given place. So, it becomes a mental game. You MUST relax, you MUST realize you have put an object in a specific spot before and can do it again.
The major issue with towers is lack of reference in close proximity to where you are aiming as it is already elevated and small. So, you must use other things to maintain a smooth and controlled hover. Look up more often, use the horizon, it is easy to get fixated on the guys below, but that presents an number of issues in terms of the time it takes to recognize a/c movement. As 170' points out, longer lines give you more lee-way, BUT, and it is a BIG but, shorter lines allow MUCH quicker reaction to movement of the object. A/c downwash being equal, I will use 50ft over 100ft if I can get away with it as I can see much more accurately. Some a/c have intense down wash, so that may not be an option.
Also, if it's not working out, fly away.... It is no good sitting there stressed out and frustrated for 15 mins hovering a potentially lethal load above a few guys. You get more tense, you get more abrupt on the controls, and you become less likely to have success. Fly away, relax, try again.
Use tag lines on the piece you are setting, it allows the ground/tower crew to grab the next bit when it is 5ft above them and slowly guide it down - MUCH easier.
Anyway, it seems most of you pundits have never done anything like this before, and to jump on someone who is simply asking a question is immature, unprofessional, and to be quite frank, juvenile.
Practicing something like this can be as simple as going and setting an empty hook on top of a sharp pine tree a few times, same same, but different.
RH