Tuesday, March 8, 2016

Winter Ski Plane Challenges in Remote Alaska

Winter flying introduces a number of duties and challenges not encountered in warm weather, but there are some advantages, too. Below are a few anecdotes from our ski plane flights, as we fly to and from our remote home in the Alaska Bush.

Warm Up:  Like any car in cold climates, we have to warm up the plane, since we do not store it in a hangar.  The day before a flight, Bryan unravels a long blue electrical cord  stored behind a cedar loveseat on our front porch, and threads it from an electric plug on the outer wall, down through the snow to the frozen lake where we have tethered the plane to two boards frozen beneath four feet of lake ice.  With the cord, he charges the plane's battery, since its performance degrades in cold temperatures.

The next day, an hour before the flight, we pre-heat the plane. When we first bought the aged plane (a 1954 Piper PA-20), the owner gave us an ancient Red Dragon heater that he had not used often.  To utilize it, we drag it down to the plane in a little black plastic sled, along with a 20 lb propane tank, a board (as a flat, hard surface for the heater), a battery charger, and a five foot long heating tube (that you shove up into the engine compartment).  Unfortunately, the tube  was so perforated with tiny holes that it took us 45 minutes to pre-heat the engine.  Not a fun wait at freezing temperatures!  Once we figured out the problem, we bought a new one for $200 that cut the time down to 15 minutes.  Well worth it.   Until... one day, when the low temperatures and the low voltage battery charger conspired to cause a near emergency.  The charger was underpowered for the job on a particularly cold day.  It had enough power to generate a hot flame but not enough to push the heat through to the plane's engine.  The tube caught fire!  We lacked a handy fire extinguisher but Bryan yanked it out of the cowling and tossed it on the snow, where the fabric sheath disintegrated into fluffy, gray ash. We learned several lessons that day.  One is to keep a fire extingisher with the dragon heater.  Another is to make sure that the bungee cords of the cowl cover are totally detached from every single hook for a rapid whisk away from the nose cone.  A  third is to utilize my snowmachine instead of the modest battery charger for future power (and the added convenience of grooming the landing strip after he departs).

Wing Covers and Gust locks:  While Bryan pre-heats the plane and performs other pre-flight checks (as you can imagine, the fuel checks occur before or after the preheater is on, never during), I remove the five black fabric covers that protect the wings, stabilizers (the small, back “wings”), and windshield from dangerous ice and snow build up which could adversely affect weight and balance as well as visibility.  The bulky cowl cover is padded (to keep the engine warm).  The one layer fabric covers are lighter, but larger.  Each wing cover is about 40 feet long and 10 feet wide, secured with numerous bungee cords on one side that click through plastic hooks on the other, with a few stabilizers wrapped around the wings, struts (diagonal metal supports for the wings) , or belly of the plane.  If the temperatures are above +10 F, my fingers are nimble in their thin glove liners, but below that threshold, I fumble with heavier mittens. Generally, it takes about 10 minutes to remove the covers and 20 minutes to install them, but this is time well spent, as the alternative is a much more time consuming task of getting rid of any ice crystals that have accumulated overnight from even the meagerest of preciptation, like morning frost.  In such a situation, we can scrape the plastic windshield and metal frame, but the sheath of the Piper is a fabric skin.  So I have to pat the wings and body all over in an effort to bounce the ice enough that it cracks and slides off.  This takes forever.  So, yea, wing covers.

Sometimes, as in sleety or damp conditions while flying/landing, the wing covers actually freeze to the wings and have to be peeled off.  Since the wings are overhead, this requires each of us to stand on the forward or aft side of the wings and simultaneously pull the covers back, inch by inch, knocking off any lens thick ice that has adhered. Then, I endeavor to shake off any additional snow and wrap up the fabric in loose bundles, bungee cords inside to avoid tangles, and shove them into the cargo hold. The four gust locks (rectangular, padded metal clamps that keep the wings from lifting in heavy winds) are stowed in a plastic bin for first retrieval once grounded.

Final Preparations:  The last project is to kick out from under each ski the wooden planks we position there to reduce the chance that the skis will freeze to the underlying ice.  Nevertheless, freezing occurs more frequently than not.  In such cases, Bryan rocks the wings and pivots the tail.  If the plane is still stuck we both push on one strut (first on one side, and then on the other) to move the plane forward in an arc.  Since usually one ski is stuck more than another, one of these methods eventually works and the plane is free to fly.

When he is ready to leave, I tow the heating supplies up hill and stow them under the porch.  Then I move my snowmachine  some distance behind his plane.  While he is gone, I will groom the landing area, by dragging a passive groomer (looks like a broken fence) behind my machine, largely in an effort to pack down any snow powder or spread it over any ice that accumulates in the shadow of the parked plane.  If his departure follows a night of snow, the propeller spits up so much fluff into the air that an ice fog forms, and I have to wait as long as ten minutes to be able to see well enough to get to work.  If I go straight inside, I turn on our aviation radio and listen to his position reports as he flies, but I always appreciate the redundant safety check of his phone call to me upon arrival.

With winter's denser cold air and skis that are so much lighter than our summer floats, take offs are extremely short.  We have measured solo departures at 375 feet and, with a passenger,  at 500 feet.  Many bush pilots like us do not need much of a landing strip.  Ours is check mark shaped: a short departure lane to the northwest and a longer one for landing, from south to north.  Winter wind direction is predictablly northern,  protracted ground fog is rare, and long distance views are stunningly clear.  So, aside from temperature, winter flights are gorgeous treats.  Our plane has a little heat knob, but it is largely ineffective for any flight under 30 minutes.  Besides, since we don't want our breath to fog the windshield, we crack the windows and,  because of all the pre-flight preparation in freezing temperatures, we are bundled up like a pair of Michelin Men.  

The trickiest part of winter flying (or any time, really) is landing.  Is there enough snow to cover a gravel runway?  Have temperatures turned a strip into an ice rink? Have freeze/thaw cycles created  a rutted pathway that can take control the trajectory of the skis (or wheels)? In remote sites, have ice fishermen dug holes and left piles of snow/ice in the lake or river?  Have beavers constructed a den above the level of the lake ?  (We have seen some the size of a row boat).  Both holes and bumps can flip a plane.  

Flat light exacerbates the problem because it reduces visibility. The term refers to   overcast days with no sun/shadow contrast to aid in depth perception.  In winter, a white/blue/gray sky looks almost identical to a white/blue/gray snow or ice lake/bog/river/landing strip.  It can be disorienting.  Some pilots fly with a roll of bright pink or orange flagging tape that they scroll out the window on a low pass, to leave a colorful ribbon on the snow.  This helps identify the elevation of the surface, but it still provides no information about any impediments (holes, bumps) which remain largely invisible in flat light. 
Ice:  This year, early winter in South Central Alaska was so warm and windy that Anchorage and the south side of the Mat-Su Valley had NO snow at the end of December.  Zip.  Nada. Then, during January, it rained 3-6 times depending on location and froze.   Without the traction of snow,  a plane on ice, just like a car, requires 3.5 to 4.5 times as much distance to stop.  But a ski plane generally has no brakes, so the conditions can be even more perilous than for a wheeled plane (which does have brakes).  For these reasons, many prudent pilots will not attempt to land on private strips which may be poorly maintained or far shorter than the 3000 -4000 feet needed to stop in slippery conditions.  Even though our plane is equipped with a STOL kit (for short take offs and landings), Bryan careened off the end of the runway we had groomed ( but since that is on a lake with 4 feet of ice, we had room to slow down).  We know a rural landowner who, over two years, painstakingly hacked and hewed and bulldozed a nice little strip in the middle of the forest.  He must have been disappointed when only one plane chose to land on it the following winter.  Too short for icy conditions.

We found that even landings on public runways were scary.  In one case, a strip was so steeply rutted that one ski became trapped, as though on a rail, and was unable to turn off the runway onto the taxiway.  We had to jump out of the plane and haul it out of the groove, grateful that no other plane was attempting to land with us in the way!  At another public airport, the extremely icy runway and the P factor of the plane (our propeller spins counterclockwise, so the plane yaws or “wants” to go left)   made it impossible to taxi slowly and straight toward the desired location, but drew the plane inexorably toward the snow berms along side. 

After a few disconcerting landings like this, Bryan talked with his mechanic about brake options. First they tried a “poor man's jerry rigged version” which is essentially a long bolt shoved through a hole on each ski.  It functions like scratchers along snowmachine treads.  The good news is that this solution does indeed grab the ice.  The bad news is it does this on take off, too, doubling the RPM level (and fuel) needed for lift off and lowering the effectiveness of the rudder (which works better at higher speeds).   After two flights, Bryan decided to bite the bullet and buy $2000 ice brakes.  These attach to the dormant brake lines that we never previously used with our floats and skis but that do function with the plane's tires (which we never use).  This clever invention works even better than car brakes because the pilot can apply each one independently of the other, using the foot pedals.  Thus, the brakes can help steer the plane on the ground, in a pivot, for example, or if the runway is icy under one ski but not the other.  It was an expensive purchase, but one that makes our winter landings much safer.

Once parked, we pull out the gust locks.  If we have arrived for a short stop, like lunch, we just throw on the padded cowl cover which will keep the engine warm for several hours.  Otherwise, we wrap everything else, too.  If Bryan is flying alone, this is a tough one-man job.  Sometimes, he can climb on top of a handy snow berm.  For other locations, he carries a lightweight step ladder which is also convenient for filling the gas tanks, which are accessed through the top of each wing.  

HOME:  When he calls to let me know that he is about to fly home, I turn on the aviation radio to hear his position reports.  When he gets close, I pull on my hefty Carhartts overalls, bunny boots, knit cap, scarf, glove liners and gloves and prepare to  haul the sleds down to the lake to carry back any groceries or other supplies he will deliver.  Like a well oiled machine, we unload the plane, install the wing covers, and loop the tie-downs throught the anchor points on the wings.  Because there are no landing lights on a remote lake strip like ours, he always returns before sunset.  Therefore, before I head down to the lake to help, I have set outside cups of our homemade wine and beer to cool for a welcome home happy hour.  We sit on the front porch in our parkas, cold drinks in mittened hands, and toast the evening sky, until it gets too cold and we retreat to the cozy, crackling warmth of the woodstove in our little log cabin.       

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