Group 4 will host a workshop with colleagues from USA on September 27 - 29, 2017 concerning the FEGS aircraft campaign. The campaign was carried out in April-May in California and Georgia, US, and was mainly aimed at the validation of the Geostationary Lightning Mapper (GLM) onboard the GOES-R satellite. The instrumentation included optical, electric field, and radiation detectors, and was hosted on a ER-2 NASA aircraft, specifically flying above thunderstorms at 20 km altitude over the continental US. Among other instruments, the system hosted a gamma-ray detector by BCSS consisting of a spare module of the ASIM high-energy detector. The main goal of the BCSS contribution was the observation of Terrestrial Gamma-ray Flashes and associated phenomena from an altitude never used before for this kind of observations. We will welcome colleagues from the University of Alabama, Huntsville, and the Naval Research Lab, to discuss data analysis and the physical interpretation of the results.