Hot plate

Finally, the ice has stopped building.

I've changed altitudes three times looking for a sweet spot that will keep more ice from sticking to my airplane. Eventually, Minneapolis Center graciously gave me a block altitude so I can work my way over and under the clouds at will.

A strong low pressure system is centered almost directly above me and has brought with it many of the associated evils that spring-time lows tend to produce. In one short flight, spanning perhaps 200 miles, I managed to fly through snow, sleet, rain, smooth air, moderate turbulence, light icing, no icing, moderate icing, strong surface winds and dead calm.

For the second time in a week I was unable to get to my ultimate destination due to the weather. Rapid City, well to the West of home was hit with a pair of blizzards. The first brought winds above 50 knots and ¼ mile visibilities so the decision not to go there was an easy one.

The second storm was more frustrating because while by the time I was ready to depart for KRAP the weather there was decent and improving the airport remained closed as they tried to deal with the ice left behind.

So instead of going to Rapid I spent both days holed up in a hotel at our intermediate stop on that route, Sioux Falls. By early afternoon the courier company had made their decision: Skip Rapid and come home with a stop in Marshall, MN to pick up freight there.

The trip from Sioux Falls to Marshall was easy and despite a bit of snow, sleet and a touch of rain the airplane remained virtually clear of ice. Even better, the temperatures near the surface were above freezing and as I descended into Marshall on the ILS what little ice there was melted and fell away. At 300 feet the runway oozed into view and I touched down with a slight tailwind.

A few minutes later I was on my way home.

At 5,000 feet there was nothing more than light icing which the airplane quite happily handled as the boots did their job keeping the leading edges clear.

Just 50 miles behind me, 5,000 feet had brought no more than a trace of ice so things had, in effect, gotten worse.

If the trend continued I could find myself in a box, relatively low and unable to climb my way out of the icing. Perversely the temperatures near home were well above freezing, tempting me to stay low and hope that things got better before they got worse.

But still, sticking around for too long in any icing conditions can quickly lead to disaster so I decided to do what the books say and requested a climb to 7,000 to get out of it.

At 7,000 feet the situation was much worse and what had been light intermittent icing at 5,000 was now moderate and continuous.

Still at climb power in level flight I lost 20 knots of airspeed in the span of a few minutes. The wings themselves stayed fairly clean as the boots did their job but the tip tanks now spouted an inch or so of jagged rime as did the engine cowlings.

I couldn't see the nose but by the loss of airspeed I was pretty sure it, along with the windscreen and anything else not protected by boots or heat held a similar amount of rime.

Enough of that then. Go up or go back down?

Normally, up would have been the call but I'd picked up enough drag from the rime that I was now in level cruise flight with climb power set and indicating 140 knots, which normally yields a nice 500 foot-per-minute climb. Not critical but about as slow as I was willing to fly the airplane under those conditions.

So down it was. At 6,500 things were better and I was in and out of clouds briefly and by working up and down within my block altitude I was able to stay mainly in the clear.

30 miles behind me a cargo airplane from a different company had made the same decision and asked for a climb out of 5,000 so I relayed what I knew: 7,000 was bad, somewhere between 6,000 and 6,500 was pretty good and 5,000 was best of all.

By the time I was 60 miles from home ATC had dropped me down even lower and 40 miles from the airport, descending through 3,600 feet the temperature suddenly went positive and I watched in amusement as the airplane began shedding large chunks of ice.

Looking back I should have either stayed at 5,000 or climbed directly to 9 or even 11,000 to minimize the time spent in the worst of it. Instead, it was the exact wrong call but yet another learning experience.