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Recue Line, "Pendulum Effect"

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This is my first post here, so hello to all.


I am not a helicopter pilot nor work directly with the helicopter industry, I became involved in


the research and development of SAR equipment some years ago, and have a few topics


regarding, helicopter SAR operations, that I have applied some interest to.


One of these is the, uncontrollable swinging of the rescue line, . . Quite awhile back I viewed a


news documentary, (I believe the location was Nevada, Arizona or California, in that ,


southwestern, three state area), that showed a flash flood victim being rescued.


The rescue crew member caught up to the victim in pretty fast running water, I believe it was


a runway designed to divert flash flood water.


The retrieval was a bit awkward since, if I remember correctly the victim was about to enter


an underpass, as the rescuer caught up with him.


In this case in, the Nevada Flash flood, I believe that it is caused by bodies in motion.


The water is flowing in one direction, the retrieve is indirect, especially in this case,


because the chopper can not perform directly overhead.


I am researching the phenomena, and am curious to know, more about it.



I have begun to mail out to individuals and companies, an inquiry


concerning this technology, . . there really is no known technical device that has compensation


capabilities, that are sufficient concerning this, "pendulum" phenomena.




The following is one of the replies to my inquiries regarding the availability of a compensator


at this time;


Date: Mon, 18 Aug 2008 14:14:15 -0700



Cliff Lawrence

Manager Operational Support

CHC Global Operations


To be honest I have not really heard about this condition referred to as this name, this raises


several questions: are they using an auto hover system (with 4 axis auto pilot) (or hand flying)


Are they using SCAS to dampen wind effect on the aircraft?


Down wash of larger aircraft can be an issue (see the problems with the


Canadian Cormorant NH90) because of swirling vortex from the rotor system


spilling off the roof and tail and hitting the Basket with varying speeds,


spins and sways..


Pilots with long lining experience seem to be better at controlling the


pendulum effect if any. (vertical referencing flying) than a horizontal


vis pilot


these are a few of the questions to be asked


Equipment to help correct the problem:


Refer: to sonar dipping with helicopters, they use a small square around


the line that automatically corrects the helicopter position over the


sonar device in the water This compensates for wind drift and current and


wave motion, they even use this in the dark


This is usually tied in with a system of auto hover called a Louis Newmark









I am looking for this video concerning the flash flood rescue, and am also interested in your



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Speaking as an old longline pilot, the pendulum effect occurs when you are not directly over your load when you lift it off the ground or in this case off of the water. When you are not centered over the load and pick it up, it swings over towards the center of the helicopter. The severity of the swing depends on how far off center you are when you pick up the load. The swing can easily be stopped by moving the ship over the swinging load when it reaches the end of it's swing. When you do it right, the load stops swinging instantly. It's easy to do if your looking out the window down at your load, but I imagine it's a little more challenging if your not flying "vertical reference" and have to rely on a spotter.

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Pete, Thanks for your reply, . .

Yes, as an observer, I think that if you have the resources to make on time moves, it is the way to go, for one thing it seems that is basically all you can do.


However, this can take a second or two, in the illustration, there is the obstacle, example,

i.e. power lines, etc.


The presence of other situations for example, having to maneuver a victim off a cliff, side of a building and so on, can put a pilot in a pretty tricky predicament.


BTW, You may not have seen the video concerning swinging and spinning, . .


Helicopter Rescue turns Dangerous



Edited by Jople
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