Sunday, March 29, 2009

Racing a Shock Wave

SeaTac is a warren of refugees right now - people camped out everywhere going on 72 hours of hoping for a seat on a plane that can make it in between volcanic explosions. So that my houseguest made it in on his first flight was astounding, nigh miraculous. More so, because the volcano exploded twice more while he was en route - the pilot must have put some serious speed on that bird, because he arrived on the wings of an ash cloud.

As I drove under blue sky to the airport, I saw a wide bank of cloud across the inlet, hiding Mt. Susitna and the Alaska Range - only the faintest of brown tinges revealed it to be an ash cloud rolling north to blanket Skwentna and the Yentna. I pulled up to the north terminal, and found it amusing that we recognized each other instantly despite the jarring unfamiliarity of having never met in person before, and quickly tossed his bags in the back.

On the way home, the high shining snowy peaks of the Chugach range shone in sunlight - except across the inlet, where they were strangely blurred. As we got closer and closer to home, the sky to the south grew yellow-brown, the mountains hidden behind a rolling wave of volcanic ash 41,000 feet high, and the still air started to move, snow streaming away north and trees bending as the shock wave from the 3:30 explosion reached us.

As I turned down my street, I saw the wall of dust at the end, having crossed the sea, now climbing up on the land and sweeping toward me - and gritting my teeth and apologizing to my poor car, I drove headlong into it. Fortunately for the poor engine, we only had a few blocks more to go - as I parked it, I could already see tiny particles of ash falling like dribbled sand onto my windshield, running down the angled glass. The air smelled of sulfur and rock, and things that set my hair on end, sharp and dry and wrong, and I hustled my poor exhausted guest inside, finding myself instinctively locking the door behind me as if to shut out things bigger and worse outside.

This morning dawned gently gray, with leaden snow-laden clouds reflected by the dirty snow beneath and threatening to melt on the way down and drizzle running water on ice. This is not the beautiful time of the year, but it certainly is interesting! And to all you praying and hoping God speed my houseguests travels - I don't doubt your prayers helped. He really shouldn't have made it!

Saturday, March 28, 2009

Accuracy by Volume

Well, Mt Redoubt missed me with the first two explosions, but it kept exploding and exploding, and finally dusted my habitation.

I am thankful it held off long enough for my houseguest to get out of town; much as I love my favorite park ranger in the whole wide world and really do intend to teach her to fly when I get my CFI no matter where in the world she ends up being posted, being under a rain of pulverized airborne magma is not the best reason for missing work. It exploded twice today to make up for that, and I'm hoping it holds off long enough for a friend to make it into town tomorrow.

Though part of me really, really, really wants it to explode during Earth Hour tomorrow. It's putting out not only more carbon dioxide than generations of poorly-thought-out "awareness-raising" stunts could save, it's also putting out atmospheric pollutants of the sulfur dioxide and pulverized rock and obsidian shard variety. Now that's a way to put hubris-ridden humans in their place.

In the meantime, volcanic ash is really bad for the car engine, and similarly bad for the human lungs. So, not much driving or errands - what to do when stuck home alone, disconsolately poking at the aviation weather sites like rubbernecking at a wreck? Why, pour a glass of local-brewed mead, clean my kitchen, pour another glass, and plot recipes. It's too late tonight to stay up cooking for hours, so crockpot corned beef it is! Tomorrow I shall use the brine to cook truly delicious potatoes, cabbage, onions, and carrots, to welcome a guest in. And should we stay off the streets, it'll provide plenty of leftovers.

Monday, March 23, 2009

On instruments and visuals

Sub-arctic sunsets are long affairs, taking full hours from the sky starting to turn to the stars coming out, and even then, as the sun slides at an oblique angle away from the horizon, still the fire rims the mountains while stars shine overhead. We'd taken off in full daylight, cold wind biting at my hands and face as I helped pull the wing covers off under the cloudless blue winter sky, and making me shiver despite four layers on my torso, biting at my legs through my jeans. The sun was already low enough that it was spilling golden light across the land, front range of mountains above the airport casting violet shadows on the mountains behind them, turning the ice fields where glaciers are born into contrasts of sharp-edged violet and gold.

For contrasts closer to home, I was very busy studying the panel layout of this unfamiliar Cessna 180 - an older example of the breed, she had a proud straight tail and far fewer pounds to weight her down than newer, feature-filled models. Taxiing an unfamiliar taildragger is always a challenge, and that I was sitting in the right seat didn't help. Under the owner's watchful eye, his hands ghosting on the yoke and rudders, I found the compromise between taxiing with ailerons forward (dive away from a tailwind) and ailerons back (keep the prop away from a soft field). The snow crunched underfoot, almost unheard above the din of a full six cylinders. Unlike a supercub, or even a PA-12, even a tailwheel Cessna is still a Cessna, and needs far less rudder input than many others. That is a lesson hard to learn, though it is better to be watching too much than fat, dumb, and happy. The secret to taxiing her is to build up a little speed, then press the brake lightly. Momentum-brake-momentum-brake-momentum-brake and she'll go where you want.

Unlike a nosewheel, she starts her takeoff roll a lot closer to flying attitude - and the controllable-pitch propeller and featherweight frame wrapped around six cylinders means all her metaphorical horses break loose and build up a lot of power very quickly - she climbs, at two people and half tanks, like a homesick angel. Like a firework. So steeply my prior experience had my body certain we were going to stall her and make a smoking hole on the runway - but after a small eternity, the vertical speed indicator still faithfully shows we are accelerating upward at a thousand feet a minute, and the manifold pressure and engine rpms are doin' just fine.

It is one of the cruel ironies of life that brand new student pilots are fixated on the gauges, (we break them of that habit early to look outside for traffic, weather, terrain, the airport they're landing at, and little things like that), but instrument rating students must then be broken from watching outside and forced to concentrate on the instruments. My copilot donned his foggles to blind him to the glorious light show outside. First we did clearing turns, wide gentle circles in the sky looking for other people around - but on a cold, windy weekday evening no traffic troubles our sky. So he transitioned into steep turns - leaning the airplane in like motorcycles lean into the curve as they 'round the bend. Just as a motorcycle must keep its front and rear tires aligned to prevent slipping or skidding across the road, so too we keep the plane's tail aligned to make the turn smooth, without losing power or position. (Besides, uncoordinated turns make people prone to airsickness turn green or grey. Sloppy practice makes for sloppy execution, so always aim for perfection.)

When putting your trust in mechanical things, it is critical to know their shortcomings, their quirks, and their modes of failure. In fact, that's good advice for people, too, but when learning to fly by instruments alone, you must remember which gauges show an instant response (even if it's wrong), and which ones are laggards. For example, the magnetic compass will show variation with every bobble and bounce of the aircraft. Unless the air is dead calm, and you're not maneuvering at all, the best to do is to average the swinging needle. On the other hand, the VSI will always lag a little behind what you're doing. If you want a 500 foot per minute climb, if you keep pulling nose up until you see the needle peg 500, you'll be doing 525 fpm. This is why you need small smooth corrections - put in a correction, hold it, and then check to see if it's had the desired effect.

When going 'round a corner, there's an instinctive reaction to grab something and help hook that turn, be it a playground trunk or the kitchen doorjamb. In the plane, the body tried to do this by taking the yoke you're already holding and pull it toward your chest. This is the wrong response - it makes the airplane climb, and airspeed drop. A student pilot usually notices about the time he starts feeling light, and corrects by shoving the nose down. this goes from 500 fpm up to 500fpm down, resulting in a micro-gravity moment of dust and gravel, loose pencils and all rising off their surfaces to hover. Then he does not realize he has put too large a correction in until you feel as though you are plummeting from the sky, often at 700-800 fpm, wind whistling through the prop as you gain speed in a dive. Inevitably, in panicked reaction, the student hauls back on the yoke, resulting in a more dramatic effect from the first time. Round and round, in your own personal roller coaster. Learning not to do that does not require overriding deep-ingrained instinct; it means scanning quickly enough to catch the problem when it's minor, and correct.

As it went, this particular pilot was doing pretty well, getting there, and we went 'round and round the sky, working on minor corrections, getting better with each pass, until he was satisfied. (Or queasy.) The sun had almost set, the mountains in the west that it rested upon dusky violet silhouettes, sky ruby behind them but for the low fiery orange sun. The pilot smiled at me, sat back, and gestured down at the wide white bands messily braided below us of a glacial river running to the sea, and said, "Want to take her down and look for moose? I saw a whole bunch the other day."

I turned until the plane was pointed at Denali, highest North American peak - and her flanks were still pink , glowing gold at the top where she stood tall enough to catch the light of the sun. He handled the throttle, talking me through the use of a manifold pressure gauge and prop control (what can I say? I'm a throttle-mixture kind of girl, without those extra controls.). Down we coasted, into purple shadows, running up the river as the altimeter unwound, looking for the darkest spots you can see as we overflew the many sandbar islands with brush and trees. The moose like to lay down in the islands, among their food and shelter - a dark indistinct shape out in the snowy stretches of ice and snow would likely be a snag, but as we skimmed down low and lower, we saw moose lying down and some standing by the edges, on the banks of islands.

I raised a wing to turn, pressing rudder gently at the same time, so that as the land upriver slowly crept up in height, we might stay in the middle, clear of the tops of the highest trees, as we checked tracks in the snow - moose, maybe wolf, definitely, here and there near habitation, those of snowmachines. As we came to a confluence, I gently pulled up a little, for the wind coming down the feeder river brought treetop-height turbulence, but fifty feet higher than the trees was as still as the winter calm can be.

Finally, our great shining beacon ahead, our measuring stick for sunset's progress, started showing that impossibly clear pink that only sunrise or sunset on snow can be, and the ten thousand shades of light between that and deep violet of near-night at the base. I turned, adding in throttle and checking with the owner on prop setting, and started a gentle climb back the way we'd come. We rose into a mountain-rimmed bowl of twilight, the open channels of the river and the ocean arm gleaming like molten pewter against the deepening sky. Night came softly, and a lone call of traffic had us straining to look - confused by a bright beacon moving oddly, but it was only an ambulance's lights. Saying a brief prayer for whomver the ambulance was going to see or bring back (for it was far out of town, hurtling down the packed ice backroads that melt to gravel in summer), we aimed for the bright lights of the Birchwood Shooting range across the ocean arm, marking the location of the airport just across the road.

No matter how much I trust the plane mechanically (and I knew her mechanic, engine time, and maintenance history well before I went looking for moose), I do not trust me to land her on an icy runway on first acquaintance - and neither, sensibly, did her owner. He took the controls on downwind, and brought her gently down, mains first, then tailwheel. As we taxied to her tiedown, the headlights of a friend approached, attracted by the distinctive sound of her engine coming in.

Tuesday, March 17, 2009

Where to find ANC-19

I keep getting hits from people searching for ANC-19, Wood Aircraft Inspection and Fabrication, which makes me consider that I'm not the only person out there combing the web for it. Because this publication looks rarer than aileron cove for a pre-WWII airplane, here's the link for all of you searching for it:

for those of you who want a hardcopy, you can get it from Essco.

Out of curiosity, who are you, and why are you looking for it? What plane are you working on, if one? Have you found any very nice sites that are full of good information, or build logs you like?

Friday, March 6, 2009

An October Flight (Introduction to my airspace)

October 2006:

The clouds had come down like a grey lid on the world, drifting over the mountains at about 4000 feet - the tops of the mountains got snarled in the clouds, merging snow and sky together. While it looked calm and still at a glance, a long, careful watch showed winds boiling over the peaks and roaring along the mountain as a low pushed its way blindly to wherever weather goes to die. But below, I could see for a hundred miles of Alaska, calling me out of the city to come play.

I took three times longer than I used to, preflighting the plane, running my fingers along the leading edge and gently acquainting myself with this new lady. Walk along the wing, looking for any bad dents, checking the pins and the counterweights, the play in the rods and the presence of the nut. It was good to come early, so the plane could introduce herself during preflight and we could get to know our differences - the fuse panel in a different layout, avionics master switch four inches over from where I looked for it, and instruments in a different order. A cherokee once surprised me with flaps that turned by crank in the ceiling, and I've met a 180 with flaps that operated by a bar pulled back from the floor like an emergency brake to full 40 degrees flap down. (That's common in supercubs, and older Cessnas, but the younger models would have you think the world ended at 35 degrees.)

This particular plane is a Cessna 172 P Model. It was produced in 1981, four years before Cessna ceased production of all light aircraft. The interior shows a trim that was absolutely pleasant back then, with a quarter-century of wear and tear in every crack of the Naugahyde and rough spot on the instrument panel. The instructor and I push her out, and climb in, adjusting our seats.

Her engine design dates back to the 1950's, and I give the engine two shots of prime before turning the key. The starter grinds, and nothing happen. The instructor looks at the prop like it's a puppy who forgot what to do when you say "Sit!" and shakes his head. "Try another two shots of prime."

We do, and the engine leaps to life. Once it remembers it's supposed to run, it's a very well-behaved happy growler, content to run smoothly at such a low idle we have to add throttle to start her rolling. Out to the taxiway, clearance from ground, and to the runway. I fumble over my radio calls, unfamiliar with my new name of "Cessna Five Two Niner Five Zero" and nickname "Niner Five Zero."

Up we go, from the quiet air in the lee of the mountain to the altitudes rich with winds. Physically, we've climbing over the eastern part of Anchorage city, passing houses crammed together and the sprawls of forested greenbelt that give us more feeling of space and freedom. Over the Moose Run golf course, where they have rules about what penalties to take if a moose gets between you and your objective, or if a fox kit pounces on your ball and runs off with it.

Before we have to try to climb over the mountains, we turn northeast and run the long gauntlet - keeping between the highway and the mountains. The highway represents a mental and regulatory barrier; beyond the car-studded asphalt ribbon below lies an army base and an air force base, and the airspace above it. There, the fighters practice traffic patterns while the C130's drop loads of soldiers by parachute to exercises below, live-fire tests are conducted, and the AWACS come home to roost.

The wind is from the south, and it keeps blowing us toward the mountains; my track is a zig-zag in the sky of slow corrections. Looking out the window and seeing the golden-swathed mountain closer and closer is beautiful, but not advisable, and we continued north. Not long after dealing with the turbulence and different airflow of the mouth of Eagle River Valley and Eklutna's Valley, we passed the end of the northward march of mountains, and turned east toward Palmer and the glaciers beyond. Silt-grey river wound beneath us, swollen with fall rain, and we sought its headwaters.

Past Palmer, the ranges started coming together again, leaving only a broad, steep-sided path ahead of us that the glacier had carved before retreating. Forward, we found a wall of white reaching far up the mountains til the clouds swallowed it; the base was composed of rumpled ridges of jagged blue-white ice, lightly gray with dust and sporting a broad black streak of dirt like a photo-negative of a skunk. At the base, a wide lake of meltwater was placidly still, and calved icebergs filled half the water with block shapes in colors from startling blue to black.

Borne on metal wings that took us higher than ravens, we flew up the glacier. Further up, the glacier splits into several separate glaciers, each coming down from their own source ice fields and mountainsides. One shone light blue-white, another was dark and dirty. All of them, toward their tops, had their sharp edges softened and colors hidden by the fresh snow of oncoming winter.

The air here was nearly still, and quite calm; we calmed the engine's growl with pulled power, and dropped to fly low over the glacier. Up close, the tumbled field at the base was full of almost-neat rows of jagged spikes, and all the crevices between were deep, deep blue. The glaciers seemed to stretch up forever, sky and mountain indistinguishable from the sources. Cool air came in the vents, clean and smelling faintly of hot engine oil and snow.

Regretfully, we turned and left for home, passing the flanking golden aspens and birch, the deep red highbush cranberry on the mountainsides and the dark spruce - gaining relative altitude by holding level as the ground dropped from walls of ice to far below us. Back, along the windy gauntlet to where home was calling with promises of a mug of hot chocolate and marshmallows, like little icebergs in a lake below.