I have made some very crude calculations. With my poor math skills this was already a great feat and I ask for forgiveness in advance for errors or complete miscalculations.
Please feel free to correct me! (Especially you Farmer1). I will again stand humble in your mathematical wizardry.
Given parameters:
Height :1000 feet or 300 meters.
Indicated Airspeed : Approximately 50 kts or 92.6 km/h or 25.72 m/s.
Size of gondola (width): 8.25 feet or 2.5 meters.
Weight of bucket
with concrete : 1500 pounds or roughly 750 kilograms.
Time for weight to drop
down from 1000 feet : 7.82 seconds.
Gravity : 9.801m/sec/sec.
Thus:
A helicopter travelling with a underslung load at 50 kts will travel at 25.72 m/s. The gondola is 2.5 meters wide. By my poor calculations the helicopter was still 201 meters away from the cable at 300 meters or 1000 feet when the load accidentally jettisoned. If the load was dropped 1/10 of a second earlier or later it would have most probably missed the gondola.
As stated earlier in the thread:
SHortshaft
Even with the ballistic coefficient of a block of concrete the aircraft would not have even reached the line when the release occurred.
Tecpilot
But to hit a round about 2,5 inches steel cable and a 2,5m wide gondola from 800-1000ft is a feasibility only mathematicians or chair seater could calculate.
Auscan
This was a one in a trillion chance happening. ( I did the math )
Cyclic Hotline
You Cyclic Hotline, is the first one to know how cut throat the industry is. Adding 5 or 10 minutes per leg will probably get you losing the job to someone else who is prepared to take the more direct route. What if there wasn’t a suitable alternate in the mountains where the concrete can be delivered or mixed. Intimately knowing the outlays of ski resorts, you should also know that access is normally a problem and the client wants his cement at 10000 feet to build the new mobile telephone tower.
Nevertheless, I am sorry, but 1/10th of a second risk is hardly any risk at all. A single line feature 2.5 meters wide, less than the width of a dual lane carriage way, is hardly a risk in open terrain where there is masses of available space to do a controlled jettison or an emergency landing or autorotation.
I will bet you that in similar circumstances, you will never hit those cables again, even if you tried everyday for the rest of your remaining flying career.
I have done some of the most dangerous underslung work I think one can do in a Bell 206 Longranger and Bell407’s. That is precision vertical referencing with underslung crews doing live power line maintenance. If anybody knows anything about calculating the risks of underslung work, I think I do.
Don’t get me wrong, I agree with you that you have to manage the risks, but, if we have to say “what if” for every single time there is the slightest risk we will never get airborne to do any underslung jobs e.g.:
What if I have tail rotor failure at 100’ over the destination building in a CBD.
What if the cable tangles and snaps and shoots into the blades and coil around the pitch change rods and I loose control over my cyclic inputs.
What if I get the load flying into the helicopter’s tail rotor.
What if we use a new inexperienced engineer or loadmaster and do not use mirrors or vertical referencing and we have a hook up.
What if there is no alternate site to do the pickup.
What if I experience wild oscillations and I have to slow down and my fuel is running low.
What if I get vortex ring state during transition to landing or LTE in the high OGE hover.
And then my personal favourite:
What if we have an accidental release exactly in that 1/10th of a second window period and hit the gondolas.
You Cyclic Hotline stated:
I will categorically state that I have NEVER been involved with any external load operation that has overflown people, or occupied premises, intentionally, at any time, nor would I permit it to happen, or be involved with it.
Also:
Dealing with a construction crew and personnel involved with the operation on the ground, is an entirely different matter than flying an external load over the general public.
I can assure you that intentionally and unintentionally, with your hundreds of lifts a day, you probably have overflown people. Construction crews and people involved in your operations are also people.
I don’t understand what the difference is between construction crew, personnel involved on the operation on the ground and the general public. People are people, you have to manage the risks with the people on your operation or on the ground involved in the operation, as you do, as you have to with the people in gondolas.
I think flying at 1000 feet instead of 500 feet was a step in the right direction.
You know, if he was at 500 feet, as required and stated in the regulations you so carefully studied and so wisely pointed out to us imbeciles or even below the allowed height at say 400 feet, he would have missed the gondolas by roughly 74.9 meters and nobody would have said a word, not even you.
In my opinion you have a greater chance of somebody dying in your operations than flying over a gondola at 1000 feet. It sound to me, deducting from what you say, that you see your people on your jobs as expendable, because “they know the risks”. How does that make you a manager of risks?? Your arguments sounds a bit hypocritical to me.
Furthermore, and I can put money on this. If that ski lift was switched off for the duration of the flights, you would have had a mob of people, who paid a lot of money to be there, bitterly complaining to management about the infringement on their skiing time, as it is their right to be on the slopes. They would have been up in arms and would have said themselves, even if in their own lack of wisdom, that there were little or no risk to themselves or others from a helicopter flying overhead at 1000 feet. Even if you had a vote, some people would still have elected to go up in the gondolas.
Self gratification and greed is some of our human downfalls. The owner / operator would also not have wanted to switch off the lifts as he also would not have wanted to lost any revenue during this time and would have approved the flights to keep the customers happy and the business coming in.
And I say this because, I would have been in front of the queue complaining angrily that there was no risks to us in the gondolas and that I wanted to go up to ski.
I would even have argued that they had to keep on flying, while we skied, so that we could get mobile phone communications up and running, as it was in the public and my interest that I could happily continue running my business while keeping mom and the kids happy on the ski slopes.
I dare you to prove me wrong…
