This dataset contains Giant Nuclei Impactor (GNI) NaCl-equivalent Sea-Salt Size Distributions collected by the NSF/NCAR GV HIAPER (Gulfstream-V High-performance Instrumented Airborne Platform for Environmental Research) aircraft (Tail Number N677F) during the ORCAS (O2/N2 Ratio and CO2 Airborne Southern Ocean Study) campaign. The size distributions are given as spherical dry radius in 97 bins each of 0.2 μm width starting from 0.8 μm (center of bin) and extending to 20 μm (center of bin).  The data were obtained by exposing polycarbonate in the free air streak outside the NSF/NCAR GV aircraft.  Slides are available for ORCAS research flights RF08, RF15 and RF17. The slides were analyzed in the NCAR/EOL/RAF GNI slide chamber, using a dual-optical microscope. Slides were inserted into a humidified chamber with a relative humidity of  90%.  The images were analyzed using an automated edge detection algorithm, and using spherical cap geometry to determine the solution drop volume. Subsequently, the equivalent dry NaCl (Sodium Chloride) equivalent radius was determined using the Kohler equation for concentrated solutions. The size distributions are intended to be used as aerosol size distributions (Giant Cloud Condensation Nuclei, GCCN) for cloud modeling studies, as aerosol size distributions for atmospheric radiation studies, and as aerosol size distributions for atmospheric chemistry studies.