The second ARM (Atmospheric Radiation Measurement) Enhanced Shortwave Experiment (ARESE II) used a single aircraft flying above the north central Oklahoma Southern Great Plains ARM central facility to measure the atmospheric absorption in the column of air between the surface and the Twin Otter altitude ceiling around 7 km on both clear and overcast days. For this experiment, three types of broadband radiometers were used to measure upwelling and downwelling shortwave flux on the aircraft at 7 km. This provided redundancy that was lacking in the first ARESE. Further, all instruments used on the ground and on the aircraft were calibrated on the ground against the same radiation standard. Preflight and postflight comparisons of the broadband instruments used on the aircraft during the flight series with the standard, and comparisons of the ground instruments with the standard during the flights, suggest agreement much better than the target uncertainty of 20 W/m2 at the 95% confidence level. Comparisons of the standard and the aircraft instruments for low-altitude passes on clear days indicate more uncertainty as expected for a nonstationary platform. The estimated uncertainty in the measured column absorption based on the difference in measured net irradiances at the surface and near 7 km at the 95% confidence level is 20 W/m2.