FTM Chapter 5

Runway Numbering

Runways are numbered accourding to their direstion. A runway running east and west would be called runway 09-27.

These numbers represent the bearings of 090 and 270 degrees with the last digit removed.

The number nearest the even 10 degrees division is used. For example, a runway bearing 134 degrees is numbered 13 at one end and 31 at the other. If an aircraft is aligned with runway 14, the compass should indicate a heading between 135 and 144 degrees.  

AIM - AGA 5. 4 - Runway Markings