November 2007 Issue


Mr. Meragerís "Letting Down Easy" (September 2007) helped remind me again of that quickly needed and often used relationship in aviation: If you travel one degree on a circle and you travel one mile, the circle has a radius of 60 miles. In other words, your distance traveled and the distance from the center of the circle has the ratio of 1:60. Remember how we used this to determine the distance we are from the NDB? Flying abeam the station, we travel one degree and note the time. The time required to fly to the NDB will be 60 times the time required to fly the single degree. Knowing our airspeed, we can compute distance from the station or, knowing the distance, our airspeed. This same "magic" ratio applies in descents, too. If you are 6000 feet (one nautical mile) from the airport, and you are 100 feet agl, you will be on a one-degree glide path (1:60). A three-degree flight path would be 300 feet agl at one nautical mile.

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