The exercise ARM15 started with measurements in Switzerland performed on June 11^th and 12^th, 2015 organized by the National Emergency Operations Centre (NEOC) under coordination from the Expert Group for Aeroradiometrics (FAR). According to the alternating schedule of the annual ARM exercises, the environs of the nuclear power plants Gösgen (KKG) and Mühleberg (KKM) were surveyed. Additionally, the environs of KKG were inspected on September 16^th during the emergency drill GNU15.
Following a request of the University of Basel additional measurements were performed in the Urseren and Piora Valleys.
Further tests with the prototype of a new airborne gammaspectrometry system and the associated data evaluation software were performed, showing performance improvements since 2014 and indicating areas, where further advancement is necessary.
The major part of the exercise consisted of the participation in the International Airborne Gamma Counting exercise AGC15 organized by the Bundesamt für Strahlenschutz (BfS) in Germany from June 14^th to 19^th, 2015. The results of the intercomparison will be evaluated, interpreted and published in detail by BfS. Thus, the presented report is limited to the documentation of the measurements performed by the Swiss team.