Large trapezoidal annealed window glass lites glaze airport control tower cabs. The authors have developed a design methodology for these lites as discussed in this paper. In developing the methodology, the authors conducted failure tests of large, trapezoidal, weathered window glass lites, obtained from the U.S. Federal Aviation Administration, under uniform pressure. They used a nonlinear finite element analysis technique for thin plates coupled with failure prediction techniques that underlay ASTM Practice for Determining the Load Resistance of Glass in Buildings (E 1300-00) to develop their design methodology. The paper summarizes the experimental data, load-induced stresses in large trapezoidal window glass lites, and the load resistance of large trapezoidal lites relative to that of rectangular window glass lites. It presents the design methodology and illustrates it with an example.