We describe the University of Wyoming King-Air flight patterns in the International H2O Project (IHOP), which were designed to sample the effects of horizontal surface heterogeneity (vegetation cover, soil characteristics, terrain) on boundary-layer structure and energy fluxes, and show some data illustrating these effects. Three 50-60 km flight tracks were set along lines of 3-4 surface stations that sampled the surface energy budget, meteorological variables, and soil properties down to about 70 cm below the surface. The tracks were spaced between SE Kansas, which received ample rainfall during IHOP, and the Oklahoma Panhandle, which was experiencing extreme drought conditions. There were two types of pattern. In the first, repeated legs were flown at 65 m along a chosen track to sample horizontal heterogeneity in fluxes; while the second pattern consisted of repeated legs at 2-4 levels within and just above the convective mixed layer, to focus on horizontal boundary-layer heterogeneity. The aircraft performed multiple soundings to locate the boundary-layer top in both types of pattern. In-situ data from the aircraft included velocity, humidity, and temperature; NDVI and surface radiometric temperature were also collected. In addition, the Wyoming Cloud Radar, a fixed-beam 95 GHz Doppler radar, documented clear-air plumes, probably by detecting small insects. The two types of data will also be used for comparisons with measurements from lidars and other radars, and evaluation and improvement of land-surface model and PBL schemes used in mesoscale models