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Nervous

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#1
I have a car show shoot upcoming that’s located very close to 380kV-800kV power lines. Needless to say I’m a little nervous after reading various power company PDF’s related to safe working distances. None of them reference aerial operations.

Tomorrow will generate calls to the power authority to learn as much as they are willing to provide. After that will come a flight test of the area using a Typhoon H as the H and 920 Plus share a similar, if not the same, flight control system. There will actually be two flight tests of the area. One a few days before the shoot and one the day of the shoot. Tomorrow I get to count insulators to estimate line voltage and nearest proximity of the displayed cars to the power lines.

This one makes me nervous.
 

Eagle's Eye Video

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#2
A pilot with your experience... if it makes you nervous, that's concerning... fine line between stretching your boundaries and meltdown. But with the power companies embracing UAVs for inspections, you hopefully will be able to get a hold of someone there that has some empirical info to base a discussion on.

So the flight path will put you between the cars and the power lines? Could lead to some compass issues / possibly GPS loss... a considerable amount of EMF comes off of those high voltage lines.
Think like a thief, and plan a continuous escape route.
 
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#4
Thanks guys. I’m more concerned with compass EMI and clear air arcing. GPS is usually not affected. OSHA publishes minimum separation distances for voltage up to 800kV. Over that the power authority has to provide a number. The magic number for under high voltage tower lines caps at 14’-20’ AGL.

I believe the displays will all be to one side of the lines but that distance may be <100’. I’m hoping the utility will be able to provide a safe minimum distance, one that I’ll likely increase for a buffer.
 
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#5
Try to put the power line thing to the back of your mind and enjoy the flight
This is why we all do this. Just be ready to turn gps off which I’m sure you have mastered by now , just in case
Hope you have a good flight!
 

DoomMeister

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#6
Pat,

The minimum separation values should be good to prevent clear air arcing to the aircraft. I think your biggest concern will be the EMI effects on the compass and hopefully the Power Co. can give you some help in that regard.
 
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#7
I used to fly a lot over those type of power lines with my Q500, I know its not even close to what you are flying but I can say I noticed not on every flight but on a lot of them when I crossed the power lines at about 100 foot clearance the Q500 would go into a sideways drift. Still going forward but not in the straight line I had intended it to do. I'm pretty sure this had to do with the compass.
Keep your distance and you should be fine but keep your eye on it also
Good luck.
 
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#8
Interesting you mention the side drift. It sounds almost exactly like what happened a couple years ago when flying another system about 10’ away from the side of a train engine that was just getting underway. In that instance it was almost like a magnet pulling the aircraft parallel to the engine.
 
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#9
A conversation with PG&E this morning provided information on safe separation distances but nothing for EMI. For those interested, PG&E publishes a pretty comprehensive rules and regulations PDF (about 900 pages long) at Greenbook Manual Online. In that document a separation table is provided in illustration 1-9. The California Code of regulations publishes a regulatory document at California Code of Regulations, Title 8, Section 2946. Provisions for Preventing Accidents Due to Proximity to Overhead Lines. with separation distance tables provided in sub section 2946.

One other document that might prove useful is one that's alleged to cover helicopter operations. California Code of Regulations, Title 8, Construction Safety Orders

Short version from the California Code of Regulations, which is the same for the PG&E document, is copied and pasted here;

General Clearances Required from Energized Overhead High-Voltage Conductors

Nominal voltage Minimum Required
(Phase to Phase) Clearance (Feet)
600........ 50,000 -6
over 50,000..... 345,000 - 10
over 345,000.... 750,000 - 16
over 750,000.... 1,000,000 - 20


Boom-type lifting or hoisting equipment clearances required from energized overhead high-voltage lines.

Nominal voltage Minimum Required
(Phase to Phase) Clearance (Feet)
600........ 50,000 -10
over 50,000..... 75,000 - 11
over 75,000..... 125,000 - 13
over 125,000.... 175,000 - 15
over 175,000.... 250,000 - 17
over 250,000.... 370,000 - 21
over 370,000.... 550,000 - 27
over 550,000.... 1,000,000 - 42

For a little fun in trying to estimate line voltage I found this table on the web extracted from the USDA-RUS Bulletin 1724e300. I will not vouch for its accuracy.
 
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#10
Good luck Pat, can't wait to hear you had fun, I have a emf detector on my smart *** phone, it seems to work but I don't know the limits, anyway don't forget the hot dogs while your flying, they might be your precooked hot lunch
 
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#14
I may be doing a truck show, do you think with all the metal there could be issues?
Truck Show » 75 Chrome Shop
Yea, I get nervous too

Possibility of issues for the truck show? There's always a possibility, especially when working around a lot of slab sided metal "structures". I'm guessing much of the work will be done at just slightly above trailer height but most of it below trailer height. That could generate some issues but you'll ultimately find out yea or nay on site.

Allow me to share and experience along with a solution that worked at that place and time. I was in a harbor shooting a Nat Geo high sided, steel hulled vessel. Initially I tried doing the shoot from a position similar to figure A. Every time the H descended below the height of the gunwale it would dance around and not respond as the control inputs were directing. After a battery and a half of poor control response (I learn slow) I moved off to the side similar to what's depicted in figure B. Instant positive change in control response and no further doubts about being able to complete the shoot. It may have just been the day, the alignment of the sun, earth, and moon, or anything else but I chalked it off to signal refraction.

My theory is the radio signals were bouncing off the side of the boat and back to the H, possible causing a signal timing issue at the controller. Moving off to the side changed the direction of a bounced signal. In principal similar to what happens when we aim a high pressure water hose at a wall. Straight on and we get the back splash, off angle and all the splash is directed away from us. I think it's something you'll want to watch for if you put the H dead on between you and a trailer. Sounds like a fun event to shoot.

Yea, I know the line drawings suck but whatcha want for free?:)
 

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#18
More like lazy;)

After letting it sit for 6 months I used an H for a test flight in the yard to verify everything worked. It did just as well as the last time flown. Went to the site for another test flight. Those wires are closer than originally thought. No problems but scared the crap out of a buzzard that wasn’t paying attention. It almost flew into the H.
 

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