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.

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