The ref code provides a simple method for interrelating the numerous specs concerning the characteristics of aerodrome so as to provide a series of AD facilities that are suitable for the A/C that are intended to operate at that AD... more will follow
4C is where the "4" is the Code number and "C" is the Code Letter. So far so good.
The code number has got to do with Aeroplane reference field length.
The code letter has got to do with a) the wing span and b) the outer main gear wheel span.
Thus "4" ~ 1800 m and over (ref field length)
& "C"~ wing span: 24 m up to but not including 36 m
and outer main gear wheel span: ~ 6 m up to but not including 9 m
I hope that helps
Annex 14, volume 1
Last edited by square leg; 4th Oct 2003 at 16:28.