Icing Strategies

Icing Strategies by Peter Cassidy
AirPlay Fourth Quarter 2011

On April 13, 2011, I was on a trip from Bangor, ME (KBGR) to Williamsport, PA (KIPT). It’s about a 3 hour flight in the Bonanza. Icing is still prevalent that time of the year in the northeast and it was forecast from 6,000’ up into the teens. In fact the weather was pretty messy with lots of moderate rain and convective activity due to a large low pressure center sitting over Long Island. We knew this was going to be a challenging flight, but it looked doable.

I fly this route often and usually do it via Albany, NY. The MEAs are over 6,000’ in some parts meaning I’d have to file 8,000’ which meant I’d be in possible icing conditions. The solution was to take a more easterly route where the MEAs are typically 3,000 to 4,000’. It’s a little bit longer going this way and it’s all on airways due to high traffic volumes; no direct-to routings in that part of the country.

We started picking up rime ice over Concord, NH at 6,000’ with an OAT of -2C so we asked ATC for 4,000’. ATC’s response was quick and clear, no. MEA on that segment of airway was 4,200’. We’re playing strictly by the rules today. I could have played the emergency card and gotten 4,200’ but we were not that desperate, yet. Even in the very busy northeast, air traffic controllers are human. Rather than leave us suffering, the controller offered an interesting option, what about climbing to 8,000’? We needed to do something, so why not give it a try. Within 500’ we were out of the icing and the temperature was increasing. At 8,000’ the OAT was +3C. Problem solved for now.

We made the rest of the flight to Williamsport at 8,000’. It did require playing close attention to things. The OAT varied continuously from +3C to -2C and we were in and out of light to moderate rain. Fortunately, we did not encounter any more icing. Noteworthy during the descent into Williamsport, the OAT went from -2C at 8,000’ to +2C at 6,000’ to -2C at 4,000’ to +7C on the ground at Williamsport.

There are several points to take away from this experience. First, controllers are on your side more than we might think. Let them help. In this case the controller offered an unusual solution. It’s probably one he has seen work before. Perhaps he had reports of warmer temperatures higher up? He never offered any rationale and the frequency was too busy to get into such a discussion.

Second, be prepared to try the unorthodox. Climbing is one strategy for dealing with ice. It’s not usually a good one for normally aspirated engines so we tend to dismiss it out of hand. That day there was no way I was going to get on top, but temperature inversions are common in winter and it can work. The temperatures were all over the map this day. They were certainly not as tidy as the forecast suggested. But it did work and the mission proceeded to a successful conclusion.

The flight that day was challenging, but its safety was never in doubt. Surface temperatures we’re well above freezing, there was no freezing rain, and there were plenty of good airports along the way if the weather turned ugly. While it had plenty of challenges, none were high risk. We train for this kind of flying.

This brings us to the one unbreakable rule for flying in icing conditions; always have an iron-clad out. You never want to be caught in icing conditions with no way to safety, even if you have deicing equipment and the aircraft is certified for flight in known icing.