Thursday, May 25, 2006

Like Lighting a Big Match

Ever seen a real live crown fire, a la forest fire? Think so? I'd bet not; if you have, you're a rare case, 'cause most folks never will, not even on TV or the movies... So what, you ask - What's the big deal? Is it that amazing?? The answer is, yes, indeed it is, so allow me to elaborate...

Do you know how big a chunk of ground 100 acres is? It's big, gang, I can tell you! OK, let's see... If an acres is 208' x 208', that's... 43,264 square feet per acre, and 100 of those would be... Yipes! 4,326,400 square feet! That's a lot of square foots, huh? OK, so, we're talking a space that, were it square, would be 2,080 feet on each side, or close to a half a mile each way. That's a chunk, no doubt about it. Can you see that in your mind's eye? Can you? OK, now see it covered with mature pine forest, trees averaging 80 to 120 feet in height, and the whole thing is thick with 'em - Got that? Mature Pine forest is nice to walk in, because there ain't a bunch of undergrowth. There's a lot of dry, crunchy needles, and a bunch of smaller Pines hoping to become big 'un's, and some scrub. Out on the open slopes, in the draws, and along avalanche chutes, there's brush, and it can get pretty thick, especially in the creek draws. OK, now take this whole thing and tilt it up to maybe about a 25 degree slope or so, with a nice curvy ridgeline at the top, and a creek draw at the bottom, all brushy and meandering... Are ya with me? Good.

OK, now, you're here because you're a Firefighter with one the three most elite fire crews in the U.S., The Alpine Interagency Hotshots, based out of Grand Canyon and Yellowstone. This fire is on steep ground, and that's your crew's specialty, the thing you train specifically for and work the most - really big fires on really steep country. Here is Montana, north of the town of Canyon Ferry, in the Helena National Forest. It's August, 1981, and it's been hot and dry here for a long time. Oh, and it's windy, too - Real windy, because this fire actually started to the west of the Missouri river and jumped over it, thanks to blowing stuff and high winds.

So, let's say you're a Line Scout, which means you're working out ahead of the crew, far enough ahead that, whereas you can hear the whine of the Stihls, it's not loud: You can hear the wind every bit as well. You're out picking the route for a new fire line, so, you're close enough to the actual fire front that you can certainly hear that, too. You're close, but not too close, because you're flagging out the new line you want the crew to follow and cut. You're picking the route based on the speed of the fire's advance, which depends, of course, on the topography, the fuel type and volume, and the fact that this fire is big enough to be effectively creating its own little weather system at its front, which pretty much any large fire does to some degree. So your line needs to be chosen such that it's still there when the crew arrives. At the pace they're cutting line, they're maybe... 10 to 15 minutes behind you. Out in front of you somewhere, not too far, is John, your Crew Boss. He's out to meet a Sector Boss and figure out what comes next, once this new line gets hooked up to the rocky outcropping at the edge of the ridge there, maybe 500 or 600 feet away. You're about 100 feet below the ridge top, on a slope of maybe 20 or 25 degrees, working east toward that ridgeline. You're not sure what comes next because, well, you ain't been there yet, and you haven't talked to John, so, for the time being, this is it, worry-wise...

You flag to the edge of the ridge, and lo and behold, on the other side there's another slope, (Duh - The other side of this little hill you're on, dummy). There's a nice rocky outcropping that might just help hold things, and standing on that is John and the sector God. The other side of this hill goes down steeply to a little creek draw. On the other side of that there's another slope, thickly forested, maybe 100 acres or so... You greet the Bosses and they ask how it's going. You tell 'em, and John calls Wade on the Motorola, who says it would be good if you started backburning toward them, because the fire's getting frisky. You can do that in this kind of place, because other than the thick needle layer on the forest floor, there's not a lot of duff or other burnable stuff between you and mineral soil. So you pull a highway flare out of your pack and head back around the corner toward the crew. The sawyers are right there now, George and Pat felling, with another team behind 'em doing the limbing and bucking. You give 'em the heads up, then step through and scratch a little 6" line through to soil. Then, you pop the flare to life. The fire front is closer now, sweeping cross-slope, and you can feel the heat as it starts to pull in air from around you; perfect for pulling in a backfire. You touch the flare to the needles on the fire side of your little scratch line and flames leap right up, growing incredibly fast: In no time the needles are flaring and biting at the sparse brush and smaller pines, as the big fire sucks them in. The flame front you've started grows, and glancing left, you can see other backfires started by the crew. There's maybe 75 feet between your backfire and the fire itself, but they're both growing vertically a bit too fast, and it's making you nervous. You're about to say something to the sawyers, but they're watching too. Pat raises an eyebrow when you glance his way. Then fire front meets backfire about 50 or 60 feet away from you, and just like that, the two cancel each other out and there's not much left but smoldering stuff. Close, but so far, so good. You head back to where the bosses are to see what comes next.

When you get there, John and the Sector God are debating whether we want to head down to the draw and then work the west ridgeline on that other slope. Neither of them sound real thrilled about the idea, but the Sector God is getting heat from his boss, who looks a lot like the SWAT Lieutenant from Hill Street Blues, and is comfortably ensconsed at Base Camp. He hasn't actually seen any of this, even from the air, but still thinks it's a great idea. The Sector God, who's obviously a good guy, listens to the Big Cheese on the radio and rolls his eyes at us: "OK, Gene, I hear ya - We'll take another look at it and let ya know, OK?" he says, and then holsters the radio, shaking his head. "Fat-Assed Know-It-All fire bosses, don't ya just hate them guys?" he chuckles, reaching for his Skoal tin. "I don't know fellas," he allows, "I jus' don't like it..." It turns out that fire had crept into and along this creek draw yesterday, and that's making him nervous. He'd had it bombed a few times, but the brush is too thick, so all that did was make it hunker down some, not go out. The three of you talk some more as the crew starts to arrive, and the Sector God decides to order up another bomber run, which he does. He turns as he ends his radio conversation and says, "They had an extra load on one a the big boys, so they'll be here in a sec..." He holsters the radio again and winks at John as he packs a big ol' dip in his lip, "Let's just see what that does..." A few moments later, a deep drone intrudes into your hearing range. The Sector God's other radio squawks, and he pulls it out and says "Yep, go ahead, we're all clear." Thirty seconds later, a small, fast twin-engine plane flashes by west to east, diving down from the ridge line and blasting over the creek draw. Following his guide's path, a moment later a red and white WWII vintage bomber lumbers over the same ridge like a huge metallic bumble bee and opens its bomb bay, releasing a thick red slurry. The smell of ammonia is immediately evident as the bomber moseys on. The slurry falls, whispy red tails trailing back toward the direction the bomber came from. It's dead on, and the brightly dyed retardent slaps into the brush down there in the draw. "Nice shot," notes the Sector God, and you agree. "Well," he asks, turning to John, "Whataya think, Boss, want to take your folks over there now?" John doesn't answer yet, he's still watching the creek draw intently. John's not your average Crew Boss. In fact, he's almost done with his Doctorate in Fire Science through the University of Washington's College of Forest Resources. He knows his fire behavior quite well, and has proven on more than one occassion to have a hell of a sixth sense about places firefighters just shouldn't be. He's got that look on his face right now.

Here's where it get's interesting. In the movies, all this would be done in super slow motion, so that you wouldn't miss anything, and all the jaw dropping detail would be drawn out and highlighted. Then, maybe the scene would be shown right after the slo-mo sequence in real time, so you got a feel for how terrifyingly powerful it all is. Of course in the real world, there ain't no slow motion, though it really doesn't matter much: You're right there, with a front row seat, and you'll never forget this for as long as you live.

Suddenly, you hear what John's been focused on, the sound of fire crackling down in that thick brush in the creek draw. What's happening is this: Fire retardent, as dropped by bombers, is basically an ammonia based fertilizer slurry. It's thick, almost viscous, and it sticks to what it's dropped on and takes the oxygen component out of the fire triangle, (Fuel, Ignition Source, and Oxygen), and makes fires go out pretty darn well. But once again, the brush down there is thick and was burning quite nicely, thank you very much. The retardent didn't put this fire out, it just made it wait a little longer to get free again... And now it's time. That last bomber load landed on top of the other retardent, and weighed the brush down a little more: That let a little more oxygen in, and now, it's ba-ack. As you watch, the brush down there quickly flares up.

John's now looking at the opposite slope and thinking about how the fire we just put down around the corner was getting particularly frisky in the vertical sense. He turns to you and says, "Get your camera man, this is gonna be good!" Now, you're standing on a rock outcropping maybe 500 feet above the creek. The other side of the draw, that 100 acre patch of woods over there, is maybe 1000 feet away, as the crow flies... And in the time it takes you to unbuckle your pack and sling it off your back, hoping to open it and get your camera, that whole hillside is gone. It goes off like somebody lighting a giant pack of matches all at once: Not individual trees lighting up, or torching one by one, but the whole damn 100 acres all at once. It roars like a hurricane and blows super-heated air like a troop of freight trains passing an arms length in front of you. The heat is immense, intense, searing; it reaches for the sky like some giant crazy offering, sending a billion sparks and limbs and needles skyward in a huge votex of flame. You dive for the ground, as does everyone else, but it's still unbelievably hot, Nomex clothes be damned. Afterwards, you will note that it melted the plastic name tags on your helmets and the lenses on your smoke goggles, and that a number of you have mild burns on patches of exposed skin. In less time than it took you to take off your pack, 100 acres of mature Pine forest is smoke-blasted history. The only pictures you have are slides of the remains, the scorched trunks and ash-strewn ground. When you do make it over there, the place looks like the moon, nothing but black, gray, and white ash, as far as you can see.

Now you see what the big deal is: That's crown fire, rarely seen even by career wildfire fighters. You never, ever forget it, if you're lucky enough to see it and survive the experience. And thanks to the grace of God and a pretty cool Sector Boss, you did.

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