(4)   Nonconforming Uses.
(a)   Marking and lighting: Upon notice from L&I, the owner of any nonconforming structure that has an adverse effect on air navigational safety as determined by the Federal Aviation Administration shall install obstruction markers or lights as deemed necessary by the FAA, so that the structures become more visible to pilots. All costs to maintain and operate such markers or lights shall be borne by the owner of the nonconforming structure.
(b)   No person shall rebuild, replace, or substantially alter any nonconforming structure or other object if, in doing so, the new or altered structure or object would present a greater hazard to air navigation, as determined by the Chief Executive Officer of Philadelphia International Airport or his or her designee, than the prior, unaltered structure or object presented at the time of adoption of this § 14-511. 421



   Amended, Bill No. 150264 (approved June 16, 2015).