Here are some miscellaneous ramblings about this incident after having flown into Buffalo every week for the past month or so, including last night:
Buffalo's main runway, 5/23, has been closed since two weeks ago and will be for the next six months. This leaves only runway 14/32 to serve this moderately busy class C airport.
Arriving from the east or south, an IFR aircraft is only able to descend to 4,000 ft until a few miles outside the initial approach fix for either of the common ILS approaches. However, flying in from the west or north, an IFR aircraft is able to drop to 2,500 feet. Many times, the difference between these two altitudes is the difference between being in the clouds for a period of time and being below the clouds (being in icing or below it). On this day, IFR aircraft were being vectored to the east for the turn onto the ILS 32. This means that BUF approach could only bring arriving aircraft down to 4,000 until closer to the initial approach fix.
AIRMETs (alerts for lower intensity, but significant weather events) for icing in clouds and precipitation exist just about every day between October and April for airspace downwind of the Great Lakes of the US. Yesterday was no exception as there was an icing AIRMET over the entire area.
Later last evening a SIGMET (alerts of potentially hazardous weather for all aircraft) for severe icing over the London, Ontario (west of Buffalo by about 60 nm), area was finally released as a result of numerous pilot reports of severe icing in that region.
All day yesterday the reports of icing in the clouds from Buffalo, NY, over to Michigan ranged from light accumulation all the way up to severe. My speculation, however, is that aircraft reporting light icing yesterday in this area were only reporting the icing they picked up as they quickly dropped through the approximately 3,000 foot layer.
In reality, icing accumulation should be reported as a function of time to accumulate, not total accumulation (in other words, if a 1/2 inch is picked up in less than 3 minutes, this would be considered severe). Pilots also tend to under-report icing, for various other reasons.
With all that said, it leaves little doubt that this aircraft had picked up some severe ice. What I am curious about is why the anti-icing equipment on this aircraft was unable to prevent the ice from forming in the first place. Does anyone know what the Lear35 has in the way of anti-icing equipment? Standard boots, heated leading edges, or a combination of both?
Perhaps it was malfunctioning equipment or perhaps it was a failure of the pilots to use the equipment in a timely fashion, I suppose.
One more point: Interesting that no one (pilots or ATC on behalf of the aircraft) in this situation declared an emergency. If an IFR aircraft suddenly experiences an uncommanded climb well above its assigned altitude, I would have though that the pilots or ATC would have declared an emergency. There is no doubt that an emergency did exist for those few minutes.
Those are my ramblings.