January 1, 2004
The logbook entry for January 29, 1989, is almost as brief as the flight itself: IFR Green Bay to Oshkosh; ILS 36; ice.
On that day, after a family visit in Green Bay, Wisconsin, my wife, Cindy, and I climb into a rented Socata Trinidad for a late afternoon flight back to DuPage Airport near Chicago. The weather forecast is typical Midwest winter gloom: 500- to 1,000-foot overcast along most of the route, with a chance of icing in the clouds. Surface temperatures are in the mid-30s, and Green Bay is marginal VFR with a 1,000-ft ceiling. After the usual preflight rituals we depart with clearance to our final altitude of 6,000 ft.
The Trinidad is nearly new, sporty looking, and a pleasure to fly. Its performance is almost identical to my Mooney 201, although it needs 250 horsepower to match the more efficient 200-hp Mooney. We reach 6,000 ft without any sign of icing, level off between layers, and settle in for a one-hour ride home as the last bit of twilight fades.
After just a few minutes Cindy says, "Look at the wing!" I switch on the flashlight and point it out the left window. The vertical ridge atop the fuel cap is now decorated with a fair amount of ice. There is also ice on the leading edge. Although it is hard to tell exactly how much has accumulated, it is certainly more than I have ever seen before. I swing the flashlight forward to check the cowling and realize that the windshield is completely opaque.
I check our position; we are about 12 miles northeast of Oshkosh. "Green Bay Departure, Trinidad Three-Alpha-Victor, we've picked up some ice at 6,000 ft, would like to divert to Oshkosh." The controller responds immediately with a vector to 180 degrees for the ILS 36 approach and a descent to 4,000 ft.
I trim the airplane for a cruise descent and turn the defroster on full. Hopefully it can melt a hole large enough to see through for landing. Suddenly I notice that our airspeed is decaying. This makes no sense — we're at full cruise power, the attitude indicator shows slightly nose down, and the vertical speed indicator shows a 500-foot-per-minute descent rate.
Now I fixate on the airspeed indicator as it drops rapidly, falling to zero within a few seconds, but the airplane is still flying just fine. Then the obvious sinks in — the pitot tube must have frozen over. I look at the pitot heat switch, and it's in the On position, just as it has been since takeoff.
Then I realize that I'm not flying the airplane any longer — it's flying me. The attitude indicator shows that we're nose low in a 30-degree bank to the right, the start of a spiral. After a moment of shock and fear, anger comes out of nowhere and takes over. Soon we're back on heading.
Time to get more help. "Mayday, Mayday, Mayday, Trinidad Three-Alpha-Victor, we've lost our airspeed indicator. Request priority to the field." Again, the controller is right on top of things, and tells me to hold the present southerly heading and descend to 2,000 ft. He says it will be a few more miles before he can turn us back north for the ILS 36 approach.
I don't have the approach plate in hand, so I ask the controller for the ILS frequency. Then more bad news: "Oshkosh is now reporting a ceiling of 250 ft and visibility one-half mile in fog. Do you wish to continue?" asks the controller. Now this isn't fair — Oshkosh was at 500 ft and a mile when I left Green Bay a few minutes ago, and now it's barely above minimums. On the other hand, I don't know if we can afford to pick up any more ice en route to another airport. We continue.
Finally the controller gives me a heading of 330 degrees to intercept the ILS 36 and hands me off to the tower. As we reach the outer marker, I start to configure the airplane for landing. Cindy immediately asks, "What are you doing that for?" Good point — let's get to the runway, and then worry about landing. I leave the gear up, flaps up, and engine levers forward. Still no forward visibility, not even a small hole near the defroster vent.
Now I realize that we're moving fast, much faster than the 90 knots that I normally use for instrument approaches. The localizer needle bangs from side to side as I try to find a heading that works and tell myself to keep the corrections small. I really don't want to miss the approach and climb back into the ice. As the needle starts to settle down, there is a soft "whump" and all of the ice on the windshield flies off. Finally something is going our way!
At 500 ft agl, I start to peek through the windshield. Nothing. I ask the tower to set the runway lights on full brightness only to find they're already set to full. At exactly 250 ft agl we break out of the overcast, and the approach lights and runway are clearly visible dead ahead. Over the numbers I lower the gear and first notch of flaps, then slowly pull the power back. After a long float, we touch down normally. Total time in the air: about 20 minutes.
I did several things wrong and several things right. First, I didn't take the "chance of icing" seriously enough. Second, we should have returned to Green Bay as soon as we detected icing — the weather was OK behind us. Instead I opted for the nearest airport, and flew into deteriorating conditions. (See " Wx Watch: Airmet-wise," page 101.)
On the upside, I did take prompt action to get the airplane to safety. I also asked for help and used the controller's superb assistance to lighten my workload. And I listened when my nonpilot wife wisely suggested that we shouldn't slow down until we had the runway made.
Then there is the element of luck. During the preflight, I checked the pitot heat by turning on the switch and observing a large ammeter deflection. After the flight I repeated the test, and saw no deflection at all. In our favor, the ice left the windshield at an opportune time, making the landing much easier.
And one final lesson learned: Practice some high-speed instrument approaches from time to time. Someday you may need to fly one for real.
D.J. Molny, AOPA 812751, holds a commercial pilot certificate with 1,300 hours total time. He now lives in sunny Colorado and flies an Extra 300L in aerobatic competition.
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