Heli vs. hideous cables
 

Hi there,

I'm a layman (except for a XC paraglider license), just a decade long fan of helicopters. Via a friend of mine (just gets his medical tomorrow) I know the owner of http://www.flymed.at, who had to get himself a EC135 (waiting for business: http://nassfeld4.it-wms.com/big_current1.jpg) as his three BO-105 have been grounded for HEMS operations by JAR OPS3, in effect in Austria since 1-Jan-2010. :sad:

After I got my (first) passenger ride aboard a BO105 and talking to the owner, I started to dig into real world helicopters vs. JAR-OPS3 on the net out of curiosity. I recently read an AS355 accident report http://versa.bmvit.gv.at/uploads/med...ar_2004_02.pdf
(rather elaborate: calculating turbine rpm from frequencies present on tourist witness videos, checking cockpit light filament condition under microscope...)
where a HEMS chopper hit a cable (low voltage power line) in the Alps, whereafter the Austrian "NTSB" recommended cable cutters as strongly suggestet HEMS equipment!

And today I found this vid
vs. that one

I'm a bit puzzled comparing these, maybe you pros can shed some light on the theme of helis vs. cables:

- why did the MedVac simply slice through them w/o effect, they even landed smoothly, no visible control issues?

- why did the second one (where the ground personnel tug on the cable) end so horribly?
- why did the tail boom break off almost instanly, when it was the main rotor who hit the cable?
- why did the whole structure of the rotor mast got torn out of the cabin? :eek:

TIA
Peter

PS: that topic caught on the me, because unmakred cables a the number two danger for paragliders, after pilot weather judgement error. :E

Its fairy simple - the cable in the first video looks like some sort of communication cable (not a power line anyway), inside you will have a soft metal which the blades will slice through without too many issues.
Cable in the second video is the complete opposite, it will not give as its designed to carry heavy loads. The helicopter is the weak link, all that energy has to go somewhere!

Wire strike protection (cable cutters) wouldn't help in either of these cases, they will only work in forward flight. They don't protect against idiots pulling the cable into your rotors, or misjudgements in tight areas.

787 is correct. It liiked like a telephone cable was cut by the S 76 tail rotor.
The A-Star pilot hit his own longline. The sudden stoppage of the main rotor blade causes a massive lateral jolt and out of balance condition that broke the tail boom and pilots seat. I've seen similar accidents that boke the pilots neck as well.

Arguably, cables are the number one or number two cause of fatal accidents in helicopters, depending on how you group the accidents.

"Arguably, cables are the number one or number two cause of fatal accidents in helicopters"

the cables don't cause the heli to go down, the number 1 cause of accidents do... pilot error!

So young yet so .........

Is it pilot error if you hit an unseen cable?

The accident in the first video must have been a pilots error...

The helicopter did not appear out of nowhere-so he must have seen the cable on the approach.

When i am going to land (and get the time, of course), i always get out of the cockpit to have a quick view about what is happening around.....

But-of course.......all of us have done stupid things in our career......fortunately, most of the times nothing "bad" is coming out of that.....

Yup, I think so. The pilot should have considered that it 'might' be there, and flown, briefed or acted accordingly. It's a harsh way to look at it, but the only pre-strike approach that will prevent strikes.

It's the same as on a motorbike: it doesn't matter whether the person who pulls out in front of you is an idiot or not, the rider is the one who suffers in the accident. So it's 'my' fault that I didn't consider what the idiot might do, or read the road ahead for possible hazards.

I'm not knocking the pilot's expertise, just making an observation about how one could approach the issue.

(Not-so-young) Lafite

a lot of pilots hit cables that they know about, and temporarily loose track of, or forget about while everything else is going on.

Im sure the pilots in the two videos above would have known the cables were there, well you would hope so!!!

"Is it Pilot error if you hit an unseen cable"?

It's not anybody else's is it??. (Except possibly in the case of the NZ incident when someone else took action that moved the cable into the disc). Yes, there may be mitigation / excuses i.e "It was difficult to see" or "It was not marked on the map" but ultimately the pilot is responsible for the safety of the aircraft - if you're going down to low-level then you know that wires are a risk and must avoid them - end of story.

I speak here as someone who has twice come very close to clattering "invisible" wires in landing sites. Fortunately i saw them at the very last minute and managed to miss them - it would have been no-one's fault but my own if i had hit them.

OH