Yesterday, a brief flight from Buffalo, NY, to Toronto had an excess of drama. Even music from the intercom — sesame street silly songs — was not funny.

It was to be a very short flight – less than half an hour, but bumpy due to gusty winds and cumulus clouds. The American and Canadian weather forecasts overlapped the area, and both indicated the possibility of icing, though none of the terminal (airport-specific) messages mentioned it. With GXRP’s deicing, I was not concerned.

Right after takeoff and climb to our 4000ft cruising altitude, Buffalo’s controllers started telling me about icing in my area. Thanks, it’s pretty light so far, we’re OK for now. They told us about another airplane just a little above us that was clear of the clouds & ice, and that we could climb up there. Thanks, we’re still OK. They told us where the cloud tops were, just in case. Thanks.

Well, after ten minutes, the icing became officially moderate, in the sense that GXRP’s deicing systems were fully needed to keep up with the rate of collection. It was time to get out, so I asked ATC for a climb. They immediately approved, and I immediately pitched up to get there. Despite the extra drag from little bits of sticky ice that the deice boots left behind, and the reduced thrust from alternate-air-fed engines, GXRP obediently but reluctantly began climbing.

About twenty seconds later, my calm demeanor was shaken when the airspeed gauge indicated that we were slowing down. Whoa, dude, am I pulling on the yoke too hard? Something up with the engines? Too much ice on the wings? I pushed the nose over right away, being rather attached to airspeed (and being cognizant of the lessons of Colgan 3407). We leveled off; engines sounded fine, all felt OK, all looked OK, except for …. still falling airspeed. A nice, steady, decreasing airspeed.

No, not nice at all. About fifteen seconds later, the indicated airspeed fell below the point at which, if “indicated” equaled “actual” airspeed, we’d stop flying. Then it went to zero. But flying we were. So it was an indication problem.

My voice must have briefly gone up about an octave, telling ATC that our pitot system appears to have iced up, and that we’d need to descend instead of climbing to leave the ice. They accommodated with an immediate re-clearance to 3000ft, just about the bottom of the clouds. I let GXRP down with a great deal of focus on all the instrumentation, including GPS-measured altitudes, not relying on the altimeter (which normally is also connected to the pitot tube).

The airplane continued to fly fine. At least it was as fine as bumpy winds and cold wet clouds would let it. We kept on ridding the wings of ice and maintaining control; after a reminder from ATC, we switched to a proper instrument approach into CYTZ; we kept talking with ATC to tell them what we knew of the problem. The situation did not escalate.

Our landing at the Toronto Island was almost routine. The airspeed gauge vaguely nudged a bit up and down, so I ignored it and judged our speed by power and ground speed. The altimeter stayed working (even without the emergency “alternate static source” being activated), and we cross-checked with the GPS throughout. We landed without flaps (worried about possible tail ice), but due to the strong ground winds, it worked out like a routine – even short – landing.

After shutting down, we walked around the plane. There was about an inch of mixed ice here and there, mostly on the unprotected surfaces (where they are tolerable in such quantities). And the pitot tube? Sure enough, it sported a cute little ice tutu. Apparently our pitot tube heater failed.

Had I accepted the Buffalo controllers’ advice at the beginning, and climbed above the clouds, there would have been less ice on the plane. On the other hand, a bunch more would have been collected later on, during descent on the approach into Toronto, when the airspeed indicator failure might have been even more distracting. I will take moderate icing more seriously in the future, and will make pitot heater checking part of the pre-flight walkaround. It would even make sense to check in-flight serviceability, except that one can’t see or feel the pitot tube in flight. So one’s stuck with indirect means such as toggling the switch while looking for the 100 Watt difference in power consumption on the electrical gauges.

UPDATE: upon further reflection, the ‘original sin’ in this chain of events is excessive confidence in the degree of robustness / redundancy of this aircraft. At great expense, is doubly redundant in certain essentials: the engines and their accessories. But it is not redundant in many other aspects (e.g., deicing systems) that can also become necessary in adverse conditions. Therefore, voluntarily flying in adverse conditions that depend on these non-redundant systems is tantamount to accepting higher-than-necessary risk.

Ah, the joys of little airplanes. Still beats the alternatives.