Never Again: Bonanza icing encounter

August 1, 2008

It was a beautiful October day with nice weather forecast throughout California. I planned on flying my Beechcraft A36 Bonanza from Bakersfield to Reno, Nevada, to attend a veterinary conference. The trip would include a stop in Fresno, to pick up a friend and fellow veterinarian who had flown with me several times before.

My Bonanza isn’t certified for flight into known icing conditions, but it does have the TKS anti-ice system. About two weeks before the Reno flight, I asked my (then) A&P mechanic to double-check the TKS in case I needed it. He said it was working fine, but was out of fluid. I didn’t think much of this at the time, and although the fluid wasn’t refilled on the day of the flight, I decided to launch anyway.

I picked up my friend at Fresno-Yosemite International Airport and the trip to Reno was a smooth VFR flight. When I woke up the next morning in Reno, I looked out the window of my hotel room to see cloudy skies. A quick check of Duats.com showed instrument conditions, but no icing reported. My friend and I checked out of our hotel rooms and headed for the airport, about a five-minute drive away.

Once at Reno/Tahoe International Airport I filed an IFR flight plan for Fresno and checked the weather. Again, no icing was reported in the vicinity, or along our planned route. My preflight inspection of the airplane revealed everything working normally, although I didn’t check the pitot heat manually to see if it was working or not.

Takeoff was normal and soon we were cruising in the clouds at 13,000 feet with an outside air temperature of 2 degrees C. Within five minutes, we heard another pilot in the Reno area report moderate icing at 14,000 feet, but so far, life was good—I was flying with the autopilot on, and the Garmin 430 was showing a ground speed of 158 knots.

A little later, approach control asked us to climb to 14,000 feet for traffic. I told her I didn’t have deicing equipment, and she responded by saying, “You are going to encounter icing at 13,000 feet, too.” At that point I should have exercised my pilot’s right to refuse the clearance on safety grounds, but didn’t. I should have asked for alternate routing and a lower altitude, but didn’t do that, either.

Instead, I rationalized the situation by thinking we were only going to be at 14,000 feet for a short time anyway.

I started the climb, and we were at 13,900 feet when all of a sudden the windscreen iced up completely, and through the side windows I could see thick ice covering the leading edges of both wings. I immediately called the controller and requested a lower altitude, and informed her of my condition.

She said she could give us lower, but not for five minutes because of terrain. Meanwhile, our groundspeed had slowed to 130 knots, with only 110 knots indicated airspeed. I had no choice but to keep flying, and re-checking my airspeed and altitude. Finally, the controller cleared us down to 13,000 feet and I started down. We were still iced up, but didn’t seem to be accumulating any new ice.

Fresno was reporting an 800-foot ceiling, and on my request Fresno Approach cleared us down to 5,000 feet. I switched off the autopilot and started descending at 750 feet per minute in IMC, and noticed the airspeed was close to 70 knots and decreasing, no doubt because of our severe ice buildup. I pushed the yoke farther forward to gain additional airspeed and prevent a stall—it never occurred to me that the low IAS could have been because of an iced-over pitot tube.

I continued the descent toward warmer air, but the airspeed was still decreasing. I pushed the throttle all the way in to gain airspeed but no luck—the altimeter was unwinding like crazy and we entered a steep spiral to the right. The airspeed was way above redline and increasing. All of this happened in just a few seconds and my friend looked scared. He could tell from my facial expression that something was seriously wrong.

I got myself together, leveled the wings, and cut the throttle while slowly raising the nose of the airplane. Although I didn’t see it blow off, the ice was gone. My friend said he saw the ice fly off the windshield. Now, at 5,000 feet, we were flying normally, but I was still confused about the whole situation. How could this have happened? I had my pitot heat on.

We were cleared for the ILS runway 29R approach into Fresno, and I saw the runway environment at about 1,200 feet msl.

I dropped off my friend in Fresno and headed to Bakersfield, again in IMC but this time no ice. After landing in Bakersfield, I turned on the pitot heat and felt it with my hand—it was cold despite being on. During my private pilot and instrument training, I had read about airspeed indicators acting like altimeters when the pitot tube is blocked; that day I actually saw it, and how dangerous it could be.

This was a very close call. I made a series of mistakes that I hope to never repeat. I should have checked the pitot tube manually as part of my preflight inspection. I should never have agreed to climb into icing conditions, and probably should have requested a re-routing or even declared an emergency rather than obey such instructions. As pilots, we are hesitant to declare an emergency, even in critical situations, but sometimes there is no alternative.

As far as life lessons go, this was an important one for me, and for my friend, too. Few people would get back into an airplane after such a close call, let alone think about becoming a pilot, but he’s taking lessons for his private pilot certificate. I admire and share his love of general aviation. All in all, it was a scary but very important lesson we both learned.

Teg Sidhu is a California-based veterinarian and multiengine-rated private pilot, as well as the owner of a Beechcraft A36 Bonanza.