January 2009 Issue

Runway Considerations

Adapting to runway conditions is critical if staying on the strip is important to you.

According to Darwinian Theory, species that do more than survive and actually thrive tend to be the ones best able to adapt to their circumstances. Transferring that perspective from biology to aviation, we can see a direct parallel: The best pilots adapt to their situation—or conditions—depending on the circumstance. Got a forecast for Level 4 or 5 weather along the route? We adapt by making a decision, maybe go around the turmoil, maybe wait for a better day. Runways are a good example. If the runway we need is the one we’ve got, we can’t automatically say, "Not going." Delaying the trip may still be the only smart response. But often, the best response is to adapt. Wet runways, icy runways, snow, slush, slopes, peaks and lengths all complicate the published runway-performance numbers for a given airplane. And all are generally surmountable, as long as the pilot-in-command knows how and why to adapt to the variables. Let’s take a look at considerations for a sloping runway, regardless of which direction. For example, we know that managing our approach speed is critical to a good outcome. But adapting to a downhill-sloping runway requires more of us than accurate speed control; it also requires us to be as slow as we can get away with, and that we touch down as close to the threshold as possible. Here’s what happens if we’re too fast when flying a generic airplane, according to a presentation by Sam Harris of V1 Aviation Training LLC: If your approach speed is five percent high, your landing distance can increase by 10 percent. For every degree of downhill slope, count on an increase in landing distance of 200 feet.

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