Stop us if you’ve heard this before:
This or similar statements appear in training manuals, articles, presentations and even in the FAA’s bank of written-test questions. It’s said so often that the original source is obscure. I tracked an early reference back to a 1982 FAA Advisory Circular, AC 20-117, “Hazards Following Ground Deicing and Ground Operations in Conditions Conducive to Icing,” which references regulations established by the Civil Aeronautics Board in 1950. While I hunted for the original test data the statement refers to, I found volumes of aerodynamic studies and accident investigations supporting its truth.