Create contour using an equation

I'm using ArcMap 10.1. I have a shapefile that is a long rectangle that represents an airport runway. The FAA has guidance that says that any building built within 20,000 feet of a runway has to be lower than an imaginary surface that moves out from the runway out at a 100 to 1 slope. In other words, if you go out 100 feet from the runway, the building can be 1 foot tall. I would like to create a contour of maximum building heights as you move away from the runway. I'm not sure at all how to do this. I appreciate any help.