Winter Flying is Here

So winter arrived for real yesterday. We got about 2 inches of snow over the course of yesterday and last night. As the afternoon rolled around my boss came by to tell me the weather looked ok to try some flights. We had a couple trips booked.

When I got out to the airport they had the Cherokee fueled and loaded up and the wing covers off already. I had to take one passenger and a load of the usual freight up to the usual destination. The AWOS was calling 1500 ft ceilings and good visibility before I took off, with the surface temperature just above freezing. I took off into a crisp 13 kt wind directly down the runway. Most of the flight we went through some mist/drizzle, so I stayed at 500 ft, knowing that the temperature up above would probably dip just below freezing, making the drizzle turn into icing conditions. I was sure to be vigilant in checking for carburetor icing. Carburetors have the interesting property of being able to ice up even in atmospheric temperatures well above freezing. Carburetors employ a bernoulli effect to create a lower pressure and draw up the fuel and mix it with the air. A side effect of this air pressure lowering is a cooling effect on the air. So even though outside air temperatures may be above freezing, its quite possible that the air in the carburetor is well below freezing temperatures.

As I left the airport area I passed the local Navajo coming back from where I was going. We gave each other a quick call to make sure we were safely separated, and he also let me know conditions up the coast were about 1500 ft ceilings, good vis underneath, with the winds on a direct crosswind to the runway. The winds weren't too strong, and I touched down lightly on a slushly and soggy gravel runway, with two tiny snow piles plowed alongside the runway.

I dropped off my passenger and unloaded the freight tromping around on the slushy gravel. I bought some winter boots about a week ago when I was down south for the last inspection, and today I was glad I did, my feet stayed warm and dry. They're kind of like a high hiking boot except with a fully rubberized foot section so they're fully waterproof up to about 3 inches, but the lace and toungue section is also fully attached to make them near-waterproof up to the full height of the boot. My summer-weight hiking boots I've been wearing all summer are cracked in the bottom of the rubber sole and no longer waterproof in the least. For the price I paid they didn't hold up to much actually, they started cracking like that 4 months after I bought them, and I haven't really abused them in the least. Don't ever buy Prospector brand boots, waste of $120. Pieces.of.crap. Hopefully my new winter Columbia brand boots hold up better. They were regular $76, but when I took them to the counter to pay for them, surprise! They were on sale for $60. Sweet deal.

Anyways, once again the cops were there to do a quick search. They've really been cracking down. They've been at the airport almost every time I've been there the last few weeks. Its good.

I took off and climbed out to head back south. I knew for the second trip since it was getting late in the day it would cool down a few degrees more, so I decided to do some experimenting and climb up to 1500 hr ft, where it would be cooler, and I could simulate what the misty conditions would do on my second trip back up north in the cooler weather. Sure enough as the temp dropped below 0 the water droplets on the window would start to freeze. That's icing, so I went back down lower where we were still in the positive temps. By the time I had made it back further south and temperature had already dropped a couple of degrees, and even at 500 it was -1. I checked the AWOS and the surface temp was reported as being right on 0.

My windshield had started collecting trace amounts of ice even down at 500 ft. I wasn't going through the drizzle for the entire flight, so the ice would collect on the windshield for a few minutes, and then sublimate off, then collect some more etc, so I never got a build-up any thicker than just a paper-thin layer, but it was icing nonetheless. I landed and my boss pulled up with another passenger with him and asked me how the weather was. I told him about the icing.

"Oh, well thats not too good, I guess we'll try the second trip in the morning."

So that was it for the day, he turned around to take the passengers back while I pushed the airplane back into its parking spot, refueled it and put the engine blanket back on. There was still a thin layer of clear ice covering the leading edges of the wings. It was only maybe the thickness of 2 or 3 pieces of paper - not thick enough to see from the cockpit with no sun to glint off of it, but it was still cool to see it up close. I've picked up a little bit of icing a couple times before in the last month, but its always been above 0 degrees on the ground and so had melted off and disappeared before I had a chance to look at it from outside the cockpit.