92 Ill. Adm. Code 16.60
Conical Surface
Section 16.60 Conical Surface
a) A
conical is a surface that extends outward and upward from the periphery of the
horizontal surface at a slope of 20 feet horizontally for each foot vertically,
for a horizontal distance of 4,000 feet.
b) The conical
surface does not include the precision instrument approach surface (see Section
16.80) and the transitional surfaces (see Section 16.90).
c) There is no conical
surface for Departmental standards.