All airport zoning regulations adopted under the Airport Zoning Act shall be reasonable and not impose any requirement or restriction which is not reasonably necessary to effectuate the purposes of the act. In determining what regulations it may adopt, each political subdivision and joint airport zoning board shall consider, among other things, the character of the flying operations expected to be conducted at the airport, the nature of the terrain within the airport hazard area, the character of the neighborhood, and the uses to which the property to be zoned is put and adaptable. If an airport layout plan has been submitted for approval to the Federal Aviation Administration with a proposed instrument runway depicted thereon and such airport layout plan is conditionally or unconditionally approved without such proposed instrument runway, the political subdivision shall adopt or revise, as necessary, airport zoning regulations to protect any approach zone for a visual runway only.