Ken,
I would suggest the site gets more average views for airport photos than for airplane photos because your site name attracts viewers seeking airport data with their search engine bringing up the site, and any aircraft photos are just a bonus to them if they further explore the site beyond airports.
Shortly after I uploaded my inflight photos of LAS in September 2010, I noted a large amount of views of McCarran International Airport in Las Vegas, way out of what I would have suspected, for example. My inflight views of Ted Stevens International Airport ANC in Anchorage from August 2007 have similarly gotten many views.
As has been said, a photo is worth a thousand words, and available airport photos in color are also viewed once on the page.