"The following account was received on Jan 19 2000:

When queried about the many x's and gridlines being laid down over downtown Columbus, Ohio, a representative of the Port Columbus Air Traffic Control Operations Station put me on hold indicating 'It might just be normal traffic." However, when the representative came back on the line he told me that 'They [the aircraft] are doing photographic work [over downtown Columbus, Ohio].' "
http://www.docstoc.com/docs/162036043/PORT-COLUMBUS-AIR-TRAFFIC-CONTROL-RESPONSE



https://en.wikipedia.org/wiki/Port_Columbus_International_Airport