Safety Check: No Ice, Please

Winter weather has arrived in the Great Lakes region, and at Sweet Helicopters (Enstrom’s sister company in Fort Wayne), our Director of Operations Keith Shivers tells me we’ve already seen our fair share of HAA and VIP flight cancelations due to unexpected icing conditions.

It should come as no surprise that helicopters are more susceptible to aircraft icing than fixed wing, and when not dealt with promptly, can lead to devastating control and performance issues.

The Aeronautical Information Manual says, “a pilot can expect icing when flying in visible precipitation, such as rain or cloud droplets, and the temperature is between 2°C and -10°C.” As a CFI, I teach students an even more conservative approach and expand the threat for ice to a range of 5°C and -20°C.

I also explain that there are three types of ice: clear, rime, and mixed. These can then be further categorized as trace, light, moderate, and severe. Freezing fog, freezing rain, and freezing drizzle can be particularly hazardous, as these conditions can lead to rapid and severe ice accumulations. Ice accumulations reduce thrust and lift as well as increase drag and weight, all of which will reduce your helicopter’s performance.

Most twin-engine turbine-powered helicopters are certified for instrument flight, but very few are certified for flight into known icing conditions. I’ve never flown in one, but in 2008, I briefly got to hangar the AW139 at KGSH, which was Leonardo’s test bed aircraft for certifying the Full Ice Protection System (FIPS). So, assuming you don’t have access to a FIPS-certified helicopter, here are three words to remember when you encounter ice: avoidance, detection, and escape.

Let’s talk about avoidance first. The best way to overcome icing is, of course, to avoid it entirely. Liz, one of Sweet Helicopters’ VIP charter pilots, called last week to say she had to divert course due to unforecasted icing. She was on her way to pick up passengers at the downtown Indy heliport (8A4). She was flying VFR and monitoring IND tower, when a “wall” of snow obscured the downtown Metro area. A Southwest crew member reported moderate ice at 3,000 feet about 10 SM west of her location.

The conditions were a recipe for disaster. There were no AIRMETS or SIGMETS in effect for icing conditions at the time, but Liz acted quickly and safely to divert to an airport north of Indianapolis. The flight was subsequently canceled. Like all our pilots, Liz is a true professional and resisted the common self-induced pressure to “press on.”

Now, let’s focus on detection. Enstrom’s Senior Technical Fellow Bayard DuPont said situational awareness is incredibly important when detecting and then dealing with ice.

“There are two ways of detecting ice on Enstroms,” he told me. “The first sign of ice is a glaze on the windscreen. This might sound obvious, but if the glaze becomes so thick you struggle to see through it, find a way to get out of it. A second sign might be high and low frequency vibrations, which are often caused by ice on the main rotor blades and/or tail rotor blades.”

Finally, once you detect ice, have an escape plan. It could be as simple as changing your heading or altitude. Or, in more severe cases, it might require an immediate landing.

My former flight instructor told me about a scary experience he had battling ice. He worked full time for a local power company, requiring him to make frequent flights in a Bell 412 between Gary, IN (KGYY) and Chicago’s O’Hare Airport (KORD). On a late January flight back from KORD, he flew at 5,000 feet in IMC over the southern edge of Lake Michigan, where he then encountered moderate icing.

He had no way of shedding the ice, so he took evasive action and descended to 3,000 feet and finally escaped the ice near the eastern shoreline. He was carrying so much ice that he had to use maximum torque on both engines just to maintain altitude. His IAS was almost 40 knots lower than it was prior to entering the ice!

Whatever the scenario, ice is dangerous and unforgiving. Winter flying can be enjoyable, but just no ice, please.

Fly safe and Merry Christmas!

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About Enstrom Helicopter

From Rudy Enstrom’s early designs in 1943 to initial testing in a Michigan Quarry in 1957 to aircraft operating on six continents, Enstrom Helicopter Corporation has maintained a reputation for safety, value and performance. Based in Menominee, Michigan and proudly made in the United States, Enstrom has a rich history for design innovation. The goal is to provide helicopters to the customer’s exact specification and deliver support and maintenance worldwide.