Water drops through power lines

[Flying Pig]

We recently had a brush fire where water drops could have been made over a set of high voltage lines. We ended up just working the flanks and the hand crews cleared around the towers. But it made me think. Obviously rain isn't an issue. Didn't know how 300 gallons may react. Anyway, one of those thinks I thought of at the time.

Edited November 29, 2014 by Flying Pig

[avbug]

Rain doesn't fall 300 gallons at a time in a single point, and yes, heavy water or water with electrolytes (think water with surfactants--foam--or retardant) can cause arcing.

 

I have seen arcing caused by dropping retardant across powerlines, and most incident commanders or ATGS (air tactical group supervisors--air attacks) won't authorize drops along, near, or over powerlines).

 

I have dropped across powerlines on a number of occasions, most of them without incident, but I've also seen fires started as the result of dropping across powerlines.

 

Powerlines also obviously represent a wire strike hazard, which is compounded when slingloading a bucket.

[iChris]

We recently had a brush fire where water drops could have been made over a set of high voltage lines.

 

But it made me think. Obviously rain isn't an issue. Didn't know how 300 gallons may react.

 

As stated in Avbug’s post above, heavy water or water with electrolytes (think water with surfactants--foam--or retardant) can cause arcing.

 

The U.S. Forest Service follows a general “Risk Management Process on this issue, unless there are extenuating circumstances (Note the Operation Section at 9:58min in the video below).

 

 

Operating near or under power lines poses unique hazards, and the following precautions should be followed to reduce potential equipment damage or injury:

 

If possible, the power company should deactivate lines in the fire area.

 

Don’t operate heavy equipment under power lines.

 

Keep all aviation activity away from power lines. Inform air attack and/or other aviation resources of the location of the power lines.

 

Don’t drive with long antennas under power lines.

 

Don’t stand near power lines during retardant drops.

 

Don’t park under power lines. The magnetic field around energized power lines can induce an electrical charge in ungrounded vehicles or equipment. This charge can shock anyone who touches the vehicle.

 

Don’t apply straight stream to power lines.

 

All personnel should be cautioned that smoke may become charged and conduct the electrical current. Deactivated transmission and distribution lines may continue to pose a hazard due to induction.

 

If power lines fall on your vehicle, DON’T leave the vehicle until the power company arrives. If the vehicle is on fire or fire is near, jump clear, don’t hang on, keep feet together, and bunny hop away.

 

Note the Operation Section at 9:58min

http://youtu.be/q5bvZIJlLXo

Edited November 29, 2014 by iChris

[avbug]

USFS doesn't prohibit drops over, or around powerlines, but I have had some incident commanders dictate that they wanted the drop elsewhere. In most cases, I've been warned about the powerlines and it's been my discretion. In some cases I've turned it down for safety or for arcing considerations, and in others I've elected to make the drop.

[Spike]

I’ve once saw smoke cause several impressive arc’s right out my window. Scared the bejesus out of me……

 

As sorta already stated, unless it’s a life-or-death situation, why do it? Let it burn through and catch it on the other side……

[Flying Pig]

The issue with this particular fire was that the towers were wood. They weren't telephone poles they were huge wood structures in an area where ground crews had to bulldoze their way in. One way would have been to approach it at a 45 deg angle and sling the water towards the bases as you turn away. The only thing out in the area was the towers otherwise they would have just probably let the fire burn out and manage it. But doing a spot drop over the tower just seemed like a really bad idea for a lot of reasons. Not to mention 2500 pounds of water hitting a wood tower is bound to break stuff. In the end the ground crews made it to the towers and used the dozer to cut lines around and water drops were done elsewhere on the fire.

Edited November 30, 2014 by Flying Pig

[avbug]

2500 lbs of water at 8 lbs a gallon is only 300 gallons; not a very big drop. If water/foam/retardant is dropped too low, it bends the fuels over and the fire burns beneath them (especially true of retardant); it actually sets up a situation in which the drop helps the fire burn through the line, while minimizing the effectivness of the drop. Some still have a hard time increasing drop height. If you're next to powerlines, your drop hight (that's the hight of the hopper, bucket, or door) should be higher than the powerline.

 

Be really careful about flying into an object and turning away to sling the load into a location. If you think vertical reference is a challenge, try converting that to a physics experiement on gravity, pendulous motion, the arc of the water, the horizontal reach of the bucket, any obstacles which may extend from the lines (like support or guy wires...in a wildfire don't expect anything to be marked, or standard), or wires extending above or from the main line), etc. then consider the effects of downdrafts and changes in local lift due to rotors in the windstream over trees and around terrain, and the perfect flight path you might have expected when you began rolling away from the structure, pole, line, etc, may have altered. We used to just call it "bad air," but the aircraft may not do what you want.

 

I've approached drops before on a descending run to the target when it looked quite good until the last second or two. Then the bottom simply fell out. If I didn't have a downhill escape already planned out, I'd have been contributing to the fire at the drop site, not attempting to put it out. AS it was, I jettisoned and followed the water principle; water flows downhill and so do I.

 

On wooden structures such as poles or powerlines, water with a foam additive is best. If you're using water from a source where it can't be tank-batched, however, then you don't have that option, and have to consider the best way to get that water onto the fire. Often a little higher is better, taking the wind into account. You won't get a deluge at the drop site, but you'll get better coverage, a little more atomization, and you will have a better chance at cooling the fire area and knocking it down or suppressing it until those on the ground can work it.

 

A prime consideration if the fire is attacking the power poles or structures, meaning now you're in a firefight on the lines themselves, is getting them powered down. The dispatcher for the agency coordinating the matter should be taking care of that with the power company. I've had power cut to lines before so we could more safely work a fire in a given area; this is usually best accomplished if the tower or powerline is downwind of the fire. More time is available. If it's you in the cockpit fighting the fire, however, you can't make that decision or that arrangement; plan your tactics to focus your drops on the fire, keep your bucket or aircraft out of the powerlines, and make sure everyone on the ground knows that you're dropping where the drop might cross the powerlines.

 

Those on the ground aren't always aware of the potential complications when an aircraft starts working the fire. This is particularly true when city or county crews or even some wildfire crews get working the fire. The level of ignorance I've seen regarding aircraft operations, from those in the field, is staggering at times. It may be you that needs to educate them, warn them to steer clear, even discuss the possibility or problem of arcing. Do that before you get wrapped up in the drops, and communicate it clearly. A little communication goes a long way. If you can save a life by reminding ground troops to hang back, it's worth the price of keying the mic.

[Flying Pig]

We have a 324 ga Bambi Bucket but it's usually cinched to 80%. Where I am, water sites aren't an issue so we usually end up making are first few runs still being topped off with gas. Right now we are using straight water out of rivers or lakes. No foam or anything. I did a short season last year, a decent amount of training and then a couple day course with the forest service with a couple old crusty pilots to gear up for this season. I'm in Florida.... Our fire season is about November-March. We've already had a couple fires. One was a controlled burn that got a little out of hand and anther was a lightening strike. I've done a full bucket on a 75' line and that can definitely get the old girl rolling around if the bucket gets swinging but for work I just hook the bucket directly to the belly.

 

Good info. Thanks

[avbug]

I worked several fire seasons in Florida in the late 90's, but was in heavy fixed wing air tankers at the time. Due to exceptionally low fuel moistures, our minimum drop height at the time of 200' was bumped up to 300' because the retardant was topping trees. The drops would break off the tree tops, putting them on the forest floor and adding to the fire. During the "fire storms" in the summer of 1999, I think it was, we were up to 400' at one point, and fuel moistures were drier than the mojave desert.

 

On one occasion. we chased a fire by flanking it with retardant, up to a body of water, somewhere northeast of Gainsville, as I recall. We used the water as a natural barrier, and the fire went out. Three weeks later we responded to a fire on the other side of the same body of water. The fire had gone down into the peat and burned under the lake. It came up on the other side and kept going. Most of us who were more accustomed to fuels and fires in the west found ourselves facing new kinds of fires, some new interesting fire behaviors, and fire personnel who had no idea how to use us as a resource.

[Flying Pig]

Most firefighting in FL is done with dozers. Mountains aren't an issue so many times the ground crews will just wait for the dozer to make a big circle around it. The helicopter comes in very handy when the fire is in the populated areas. You'll have entire neighborhoods scattered in thing wooded areas of pine and oak trees. When the palmetto burns it's very oily and puts off thick black smoke like burning rubber.

Fires on the mountains would be interesting. But for now..... Fire on the beach are fine too

[avbug]

One of the things in Florida that we hadn't come across before when working a fire was the hazard of an alligator. A lot of unique ground equipment (and tactics) were in play. One day we had a crew that couldn't move up a road in a swamp area because a large alligator was laying across the road and wouldn't move. That was something I hadn't encountered on a fire before.

 

Palmetto and other green fuels that burned quite intensely were another factor there that I didn't have experience with when I first began working in the state. The fire behavior is different, and unless the fuels are physically moved, extinguishing them with water or with agents can be difficult, and sometimes nearly impossible.

 

No mountains (I think standing on a pickup truck in Florida qualifies as a high altitude experience), but some nasty, tall towers with wires extending a considerable distance away from the tower, were out there. We had days when the clouds came in and we bumped up a little higher, sometimes into the cloud, but the towers extended quite a way into the cloud. Big hazards. I recall a fire southwest of Brooksville in which we were dropping into the smoke column. The lead advised the timing for the drop as we wouldn't see the target. Count three, punch off all doors at coverage level 8 (2000 gallons), on exit break hard left, he was going right. When we broke out and rolled, we saw why; there was a really large tower just on the other side of the smoke column that we couldn't see on the approach.

 

The experience down there that really stuck with me was a comment made by a DNR pilot on a fire near Punta Gorda. It was rocking and rolling in tall timber, wind driven, with a flame front that was probably about a mile and a half long, and fairly even. We were the only heavy tanker in the state at the time, loading out of Ocala, I think. The DNR representative was in a single engine Cessna, and acting as the air attack for the fire. He told us to hit the head of the fire.

 

Hitting the head is false doctrine, a dangerous practice, and something that only an amateur would do. It has no anchor point, it splits the head and usually makes the fire worse, and is often the most dangerous place to work. Along the left flank there was a structure, and we determined that we could box the structure with retardant; four drops, door doors each, and advised the air attack.

 

"No, that's not the Florida style!" He said, with a thick, southern drawl. "In Florida, we hit the head!"

 

We advised that a structure was threatened, and would soon be lost if we didn't act. We reminded him that we were the only retardant resource available, with a one hour turn time at a minimum. Flame lengths were 150-200' and rolling, and the fire would soon be crossing a highway, and passing into heavy fuels. Our paltry 2000 gallons across a small part of the head would be tantamount to spitting in a furnace.

 

No, he insisted. It's not the Florida style. Style? Style? There's a style to firefighting? It's about looks and popularity? Turns out that news cameras were watching and he wanted a shot of a heavy tanker hitting the head, for the evening news. It was his fire to call, so we hit the head. The fire took the structure, jumped the highway, and did all kinds of damage, but at least he got his "style."

 

I've been involved in three night drops in my fire career. Two were in Florida; one outside Tallahassee, and one just outside Disney World. One guy staring at the instruments and making call-outs, the other staring at the rotating beacon of the leadplane Baron throughout the drop. Never saw the fire. Disorienting. The other one was in California on an urban interface fire, and was in a bowl in mountainous terrain, but the area was so lit up by fire that it wasn't bad. Times have changed. Last year, the USFS used NVG's on a fire at night with helicopters in California, for the first time.

[Flying Pig]

That must have been old school.......but I can definitely hear the southern accent as I read your post we just work the flanks and do personnel and equipment protection. As the dozer is cutting a line we will cool down areas in advance of the dozer, or work the opposite flank while the dozer is making its way around, looking for spot fires outside the line and generally just trying to do something productive. Sometimes the command aircraft is overhead, but most of the time its just us communicating directly with the IC on the ground. The air commanders typically use a C182 or sometimes a Navajo.

 

Yes, working a fire from the ground perspective could put a firefighter head on with stampede of all sorts of poisonous flesh eating critters. They really try to avoid putting people on the ground if possible because, no joke, you could step over a clump of bushes headed to your area and step on a 10' gator who is scared and needs a hug or a nest of water moccasins. The towers here come out of nowhere. When I flew in CA it wasn't so much of a factor because most towers were on hill tops or mountain tops... here 1300-2500' towers are all over with no rhyme or reason to their placement.

 

Its a good time though... not a bad place to do fire with my so far limited experiences with it. The FFS seems to be a decent organization with some older professional pilots. So far the pilots all strike me as older guys who have transitioned to FL as a way to relocate and will ride out their careers here flying Super Hueys and sunning themselves on the beach and waxing their tail booms in the off season

Edited December 1, 2014 by Flying Pig

[avbug]

There are far worse places to end up. I enjoyed working in Florida.