First of all, can you see why I am always squawking about how much fun it is to glacier bike ? Look at that ice! It’s perfect! The ice forms some amazing contours and they are a blast to ride.
Anyways, I chose this picture because it demonstrates well an optical illusion created by the glaciers. It is easy to determine the size of a rock if it is sitting next to a tree because we know approximately how big trees are. On the glacier rocks sit alone on the ice and the brain becomes uncertain. It’s best to judge correctly because even my 35″ tires have their limitations. The problem of determining size carries over to rising terrain as is pictured above. How tall is that hill of ice, and how far away is it ? Both of those questions are crucial in determining which way a departure will be made. The wind blows down-hill on glaciers 95% of the time and it is often a pretty stiff breeze, like 15-25 mph. Unlike the wind in the mountain valleys the wind on the glacier is often very consistent allowing a stable approach well below normal landing speed. Sometimes we will land on the glacier fully loaded and only roll 50 feet, It’s great. The problem is taking-off, which is better … up-hill with the head-wind or down-hill with the tail-wind ? This is where it is SO important to know your airplane. It’s a tough decision because neither option is very good, and the consequences weigh heavy.
In my Super Cub, I will normally take the downhill with the tailwind option, because it is so scary to out-climb rising terrain. On the other hand if I am on a Glacier I will often go up-hill because the air coming down glacier is cold and dense and steady so the Super Cub performs like a rocket ship (I realize that is a rough analogy for the Cub :o) Believe it or not in the picture above I can take-off right over that ice mound (it’s a stock 160HP Super Cub) loaded with a client and 70 lbs of gear. It looks horrible though, doesn’t it ? What gets people in trouble is that they will try to out climb something like this and then get uncomfortable and start a downwind turn … this is where it gets ugly because you are climbing at a relatively low airspeed, and then to throw a turn in there you give up the horizontal component of lift. On top of that you are loosing the headwind as you turn, and the plane begins to sag and the ground is getting closer so you step on the rudder to hurry the turn and BANG! the high wing gives up as the critical angle of attack is exceeded and the airplane enters an incipient spin at 100′ off the ground … bad ending. It is absolutely pertinent when doing flying like this that you be proficient because the margins are thin at times. Mike and I do NOT fly “tricked-out” Super Cubs with all the mods, we just fly more than anybody else so we know our Cubs very, very well.
If you want to see terrain like this then drive North out of Anchorage about 2 hours to Sheep Mountain, and we will go on a little flight. I guarantee you will never forget it. Most Alaskans don’t even know what’s out there.