SAFETY: Commentary on icing

Commentary by Neptunus Lex a recently retired USN F-18 Pilot, multi-cruise Squadron Commander and TOPGUN Instructor.

Known Ice
February 13th, 2009 · Flying
Military aviators tend to look at commercial airline flying as the “easy” life. The machines are very highly automated with redundant systems, the pay is generally very good (0r used to be), and the bed waiting on the other end comes with room service. You never have to throw yourself at the ground with high explosive ordnance under the wings, people rarely shoot at you and - at least for the Navy guys - the runway doesn’t move. Once you’ve put the jet to bed, your “real work” isn’t waiting for you on the ground. Get the machine safely on deck at your destination and your real work is done.

Sure, there’s a lot of responsibility. A commercial airline pilot “on the line” has the lives of many, many people in his hands. But if he takes good care of the life occupying his own seat - and he’s motivated to, the pilot is the first guy to the scene of most accidents - everyone else should be OK as well.

But the airline folks will fly into weather that military aviators wouldn’t brief in. They’ll shoot approaches well below the limits for a single-piloted aircraft. And they get paid for getting the pax/cargo to their destinations. If “get-there-itis” is a psychological hazard for a military pilot, for the airline guy, it’s an occupational one.

Take icing, for example. Anytime an aircraft is flying at or around the freezing level in conditions of visible moisture - clouds, rain, fog - ice can form on exposed surfaces. It can alter the aerodynamics of the wings and control surfaces, stop up pitot-static systems used to determine altitude and airspeed, and reduce engine performance, all of which can prove fatal, especially when low to the ground. Especially when on an approach to land, where the performance margins are most constrained.

Wind tunnel and flight tests have shown that frost, snow, and ice accumulations (on the leading edge or upper surface of the wing) no thicker or rougher than a piece of coarse sandpaper can reduce lift by 30 percent and increase drag up to 40 percent. Larger accretions can reduce lift even more and can increase drag by 80 percent or more.

FA-18 pilots are forbidden to fly in conditions of known ice, and if icing is encountered they must steer out of the weather, speed up and/or change to a safer altitude - anything to get the jet outside the critical 0° to +5° C band. When I browse through the online pages of controller.com and read of light aircraft equipped with “known ice” capabilities - wing boots, heating systems, de-ice fluids - I wonder to myself, who on earth would want that temptation? Who would want to have the option of flying into known ice?

It’s one thing to have an extra safety margin in pocket if the weather unexpectedly turns to squeeze. But a known ice certification carries with it at least the tacit implication that it’d be OK to fly into known icing conditions - a thought which my mind, conditioned by stern abjurations reinforced by bad memories - rebels against.

But the airline bubbas have a place to be, and sometimes that place is freezing cold, and sometimes there’s bad weather.

I don’t know whether the Bombardier Dash 8 Q400 that flew into the ground near Buffalo last night went down because of icing. But I suspect that it did.

It’s a tragedy, either way.