Bonanza 36
Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 45; Flight Crew Total 775; Flight Crew Type 350
Human-Machine Interface; Fatigue; Situational Awareness
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; General Declared Emergency
Human Factors; Aircraft; Weather
Our plan was to fly our known icing certified; turbo-normalized and oxygen equipped Bonanza from MI; to the West Coast. We left early in the morning with two fuel stops planned and lunch. At the last fuel stop we obtained a weather briefing through the Foreflight App. This was my first mistake. I should have obtained a full briefing from Flight Service. The weather called for portions of IMC; thunderstorms; and areas of icing over the mountains to the west. It appeared that we could pass these areas to the north. In cruise at 16;000 MSL the temperature was below freezing so I activated the TKS deicing system. With the TKS deice system on max we encountered an area of freezing rain in three separate bursts that overwhelmed the deice system. First the Garmin GTN 750 COMM 1 failed. I was able to keep sporadic contact with Center on COMM 2. I assume the GTN 750 antenna was covered with ice. Shortly thereafter we began quickly losing airspeed. I firewalled the throttle; prop and mixture but the speed continued to decline. I then started to drop the nose to gain airspeed. We then went into an uncontrolled steep dive. Everything lose flew around inside the aircraft. The G500 system at some point quit and went red leaving me with nothing other than my standby vacuum attitude indicator. I was able to pull out of the dive at about 11;600 to 12;000 but we were still in IMC and below zero degrees C. During the dive I declared an emergency with ATC. It was the most scared I have ever been in my entire life. I think we were moments away from either structural failure or hitting a mountain. ATC was a great help and allowed us to go as low as possible. Our problems continued in very turbulent IMC. We then had a second loss of airspeed with a more controlled descent. It was during this second event that I finally realized that I had failed to turn on the pitot heat. In hindsight; it's obvious there was never an airspeed problem in the first place. Within seconds after turning on the pitot heat the airspeed indicator began working properly. We completed the flight without further incident. While it might be easy to blame this incident on the failure to turn on the pitot heat; there was definitely an icing problem on the plane. The primary engine air intake froze over and the alternate air door popped open as designed. I was so focused on making sure the TKS system was working properly I missed the most basic of rules and failed to turn on pitot heat in icing conditions. Stupid. In addition; I was fatigued and never should have attempted a flight of this distance in one day. In addition; perhaps a real weather briefing with Flight Service would have led me to stay on the ground. Although this in no way excuses my actions; on my prior aircraft; a Cessna 182S; there was a very obvious warning placard warning you to use pitot heat. There is no similar placard on the Bonanza.
BE36 pilot reports encountering icing conditions at 16;000 FT that seem to overwhelm his TKS deice system. Loss of airspeed indication is also reported resulting in an uncontrolled descent to 12;000 FT. At this time it is discovered that the pitot heat system is not on. With pitot heat on airspeed indication returns to normal and the flight continues to destination.