rule of sixty

rule of sixty

[′rül əv ′siks·tē]
(navigation)
An air navigation rule of thumb which states that for each mile off course in a 60-mile leg, the correction to parallel the original course is 1°.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

one-in-sixty rule

one-in-sixty ruleclick for a larger image
This rule says that one unit of distance subtends an angle of one degree at 60 units of distance. For example, a chord of 5 miles will subtend an angle of 5° at 60 miles and 2½° at 120 miles. Also called the rule of sixty.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved