[CQ-Contest] Tower safety

[K9MA]

As I understand it, Paul had a "single point failure". When the pulley 
failed, there was no backup.

The main idea of fall protection is to eliminate single point failures, 
the idea being that multiple simultaneous failures are much less likely. 
(The same principle applies to designing high reliability electronics 
and other systems.) For example, when climbing a tower with a fall 
arrest system, it is the backup for your hands and feet and vice versa. 
When you attach the positioning lanyard, the fall arrest system is its 
backup, so you can let go of the tower. When I do something particularly 
risky, like climbing onto the top plate, I'll have two fall arrest 
lanyards attached, as the hands and feet aren't so secure then.

As has been pointed out, the hand, feet, and associated control system 
are particularly unreliable, so it's good to back them up.


73,
Scott K9MA



On 11/15/2019 18:43, K8MR via CQ-Contest wrote:
>   My understanding is that rather than climbing the tower, Paul was being hauled up by a winch. The pulley at the top of the tower failed, resulting in the fatal fall.
> Man lifts are heavily regulated by OSHA, though I'm not familiar with those details. However, it is not possible to be attached to a tower while going up or down on a man lift.
> When erecting a new 750 foot tower in 1999 at WJW-TV, where I was the transmitter supervisor, there was a serious accident involving such man lifts. A relatively new climber was coming down on the line after a day on the tower, watching where his feet were going to land, while balancing himself against the line. He did not notice that the line went through a large pulley at the bottom, and lost several fingers when they were caught in that pulley.
>
>
> 73  -  Jim  K8MR
>   
>   
> -----Original Message-----
> From: Edward Sawyer <EdwardS at sbelectronics.com>
> To: w1ve at yccc.org <w1ve at yccc.org>
> Cc: James Cain <jamesdavidcain at gmail.com>; rjairam at gmail.com <rjairam at gmail.com>; CQ-Contest Reflector <cq-contest at contesting.com>
> Sent: Fri, Nov 15, 2019 6:27 pm
> Subject: Re: [CQ-Contest] Tower safety
>
> I have not heard the exact circumstances of W0AIH’s accident.  What was quickly published was his fall arrest system failed.  He was clearly using a harness.  If some has the details, I think we would all benefit from learning.
>
> Even with proper temporary guying, I would not climb a tower to take it down that had the base legs rusted through at the concrete point.
>
> We would really benefit from the equivalent of NASA’s pilot reporting system where the details of events and “near events” are publicized for us all to learn.
>
> I for one, like many tower climbers that I have observed, do a hybrid of free climb and clipped in.  Free climb to the first set of guys is pretty common for many of us.  Clipping in as we gain height.  90% of the time clipped in while climbing.  100% doing work.  Full body harness?  Not really.  But haven’t used a lineman’s belt since being a teenager.
>
> Is it perfect?  No. But if I am tired. I don’t climb.  And the above is pretty darned safe when done with good judgment.  A full body harness and carelessness, or understanding of physical strength, is not “safe” just because.
>
> Ed  N1UR
>
> From: Gerry Hull [mailto:gerry at yccc.org]
> Sent: Friday, November 15, 2019 4:14 PM
> To: Edward Sawyer
> Cc: rjairam at gmail.com; James Cain; CQ-Contest Reflector
> Subject: Re: [CQ-Contest] Tower safety
>
> Ed,
>
> I think you are applying your analysis from the wrong perspective.
>
> In the W0AIH case, if Paul had been 100% attached to the tower, his winch cable could have failed and he would have survived (this craziest) winching approach.
>
> In our local case, the tower base failure as a root cause is a red herring:  It may have contributed.  However, it was a process error.  No one should consider taking down a tower that was up for ANY length of time without first fully inspecting the tower, the guying system, etc.  Had these unfortunate gentlemen taken any time to survey and understand what they were getting into, I believe this incident may have been avoided.
>
> As K8MR points out, it does not matter how many 1000s of hours of experience you have, or how much of a bodybuilder you are.  All it takes is 1 second of distraction to end your life.
>
> 73, Gerry W1VE
>
>
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-- 
Scott  K9MA

k9ma at sdellington.us