This article, which originally appeared in the May 1998 issue of "Mathematics Teaching in the Middle School," explores the runway numbering system. The activity described in this paper furnishes an excellent setting for discussing rounding rules and, in particular, what to do if the digit to the right of the place to be rounded is equal to five. A discussion of parallel lines and segments also proves very interesting and can lead to a lesson about "if and then" statements and logic. Detailed artwork illustrates the numbering system and how pilots know which runway to land on. (Contains 6 figures.)