IFR Fix: Nerves of ice

An airspeed alert from the first officer prompted the captain to increase pitch even more, and up they went, in instrument conditions and turbulence. It was only when the pilot glanced at the right-seater’s airspeed indication of 110 knots that the aircraft’s fantastic performance was revealed as a hoax—a surprise quickly followed by a stall and the jet's automated recovery response.

Next came a secondary stall during a 6,000-foot altitude loss as the pilot struggled for control. Finally able to troubleshoot (as the right-seater calmed the passengers) the pilot discovered that a previously balky left-side pitot heat circuit breaker had again “popped,” allowing the pitot system to freeze, according to the pilot’s report to the Aviation Safety Reporting System.

Icing in a thunderstorm can strike in any season. If you have been keeping track of aviation weather lately, you likely have noticed that the risk of an icing encounter in clouds or precip in routine flying is making its way back into the lower altitudes.

Time to refocus on the icing hazard for the season’s instrument flying. To avoid surprises, note how the circulation of air around pressure systems distributes cold air and moisture horizontally and vertically in the atmosphere.

Ice is famously unpredictable. Many harrowing icing stories begin with the pilot declaring that icing had not been included in a preflight forecast.

“There was no mention in a briefing for ice,” began one ASRS report by a fixed-gear single-engine airplane pilot reporting a chilling encounter that began 10 miles out on an RNAV approach to Creve Coeur Airport in St. Louis.

The icing began with a light coating of rime, but quickly became a nightmarish accretion of “freezing rain and clear/rime mixed with jagged edges on my leading edges.”

Then another complication—"a useless ice-covered windscreen”—confronted the pilot who was hand-flying the compromised airplane “to avoid autopilot disconnect and un-commanded aerobatics.”

The flight descended through reported cloud bases at 2,000 feet and broke out, but the pilot had difficulty locating the airport. It appeared from just above minimums after “some mild excursions”—allowing the flight to circle to land with “no damage to anything but the pilot's nerves.”