Proper Approach Airspeed
The concept of proper airspeed control for the approach to a mountain airstrip cannot be over emphasized.
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The landing distance will increase by the square of the ratio of the touchdown speed to the normal touchdown speed. |
| In this
example, we use 55 for the actual touchdown speed divided by
the normal touchdown speed. This ratio is 1.1 or a
10-percent increase in speed. The landing distance increased
by the square of the ratio or 21 percent increase in landing
distance.
You might think, that's not too bad. I only need 1,200 feet to land, so what's another 252 feet (1,200 x 1.21 = 1,452)? |
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| Once you
start believing, "What's another 252 feet," it displays the
beginning of complacency. Or, maybe you decide to add an
extra 5 knots for the wife, another 5 knots for the kids and
another 5 knots for the dog. In this example, we change the
approach speed to 70. The ratio become 1.4, and squaring the
ratio means there is a 96-percent increase in landing
distance.
Ask yourself, do I want to nearly double my landing distance on a short mountain airstrip? If not, use exact airspeed control.
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