Sorry, but both Pontius Navigator and Gainsey's crusty old Pathfinder Master Pilot are indeed wrong.
From the College-of-Arms:
Q. What is a crest?
A. It is a popular misconception that the word 'crest' describes a whole coat of arms or any heraldic device. It does not. A crest is a specific part of a full achievement of arms: the three-dimensional object placed on top of the helm.
If you look at the RAF College Coat of Arms here:
http://www.cranwell.raf.mod.uk/Organ...e/COATARMS.htm, the heraldic terms are well explained.