November 2008 Issue

Aircraft Departure Downdraft

Right after takeoff—when we’re low, slow and heavy—is a lousy time to encounter convective activity.

Shortly after receiving my instrument rating, I had occasion to help ferry a Piper Archer a whole dozen miles. It was the dead of winter, dark, and snowing. The snow was dry and the temperature too low for it to stick to the Archer, itself cold-soaked. Even though I was as instrument-current as it gets, my comfort level was too low to tackle this. It promised to be a high-workload flight in conditions I had never experienced. I declined, and someone more comfortable with those conditions handled the flight uneventfully. That was the first time a daunting instrument departure overcame my concern with an approach at the other end. But not the last. These days, in fact, I’m usually a lot less concerned about an approach to minimums than I am a takeoff involving challenging weather. An instrument departure into real weather can be the greatest challenge a pilot will face: The airplane is heavier than it will be at any other point in the flight, we’re at a low altitude and airspeed, and—while we’ve performed a thorough pre-flight—there’s always the nagging doubt we’ve forgotten something. Sometimes, we can find ourselves taking off into weather poor enough that it prevents returning to the departure runway if we need to. Add to this mix a lack of subjective knowledge of how the weather will affect us, and the challenge of an instrument departure becomes much greater than an approach to minimums after a length of time "wearing" the airplane and the flight conditions.

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