1000 LAWS OF MARYLAND. [CH. 422

political subdivisions in which the airport is wholly or par-
tially located does not approve the same, it shall notify in
writing the political subdivision, submitting the same, of such
disapproval with its reasons therefor. The action of the
governing body of the political subdivision in which the air-
port is wholly or partially located on such rules and regula-
tions or any amendments thereto shall be final and binding.
In every case of the submission of any such rules and regula-
tions or amendments thereto, the governing body of the
political subdivision in which the airport is wholly or partially
located shall act thereon in not less than sixty days from the
date of such submission and if it does not act thereon within
that time, then the same shall become valid and effective with-
out the approval of the governing body of the political sub-
division in which the airport is wholly or partially located. In
case of conflict with any airport zoning or other regulations
adopted by any other political subdivision, the airport zoning
regulations adopted pursuant to this subparagraph shall
prevail.

(5) All airport zoning regulations adopted under this sub-
title shall be reasonable, and none shall require the removal,
lowering, or other change or alteration of any structure or
tree not conforming to the regulations when adopted or re-
vised, or otherwise interfere with the continuance of any non-
conforming use.

(d) (Permits and Variances. )

(1), (Permits. ) Where advisable to facilitate the enforce-
ment of airport zoning regulations adopted pursuant to this
sub-title, a system may be established and regulations may
be adopted by any political subdivision for the granting of
permits to establish or construct new structures or new uses
of land or structures or to replace existing structures or
uses of land or structures or to make substantial changes
therein or thereon or substantial repairs thereto. In any
event, before any non-conforming structure or tree may be
reconstructed, replaced, substantially altered or repaired, re-
built, allowed to grow higher, or replanted, a permit must be
secured from the administrative agency authorized to ad-
minister and enforce the zoning regulations, authorizing such
replacement, change or repair before any work is started, and
no such permit shall be granted that would allow the struc-
ture or tree in question to be made or become higher or
become a greater hazard to air navigation than it was when
the applicable zoning regulation was adopted. All applica-
tions for permits for replacement, change or repair of non-
conforming uses, structures or trees shall be granted as a