A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Gary LaPook
Date: 2016 Nov 23, 22:36 -0800
In the U.S. the Federal Aviation Regulations were changed in 1973 to require that airspeed indicators had henceforth to be marked in knots and manuals should specify speeds in knots. Prior to then it was common to see airspeed indicators in mph. Manufacturors like mph because you get a bigger number which impresses people. A Mooney makes a plane that flys at 175 knots (201 mph) which makes it easier to sell this plane if you call it a "Mooney 201" instead of calling it a "Mooney 175."