The GOES-R PLT Geostationary Coastal and Air Pollution Event (GEO-CAPE) Airborne Simulator (GCAS) dataset consist of solar backscattered radiation measured by the Geostationary Coastal and Air Pollution Event (GEO-CAPE) Airborne Simulator (GCAS) flown aboard a NASA ER-2 high-altitude aircraft during the GOES-R Post Launch Test (PLT) field campaign. The GOES-R PLT field campaign took place from March to May of 2017 in support of post-launch L1B product validation of the Advanced Baseline Image (ABI) and the Geostationary Lightning Mapper (GLM). Data files in HDF-5 format are available for March 21, 2017 through May 14, 2017.