Penetrating into the stratosphere to research climate, flying over the North and South poles, and travelling to far-flung corners of the world to collect atmospheric data: This is the scope of applications for the one-of-a-kind HALO research aircraft (HALO stands for High Altitude and Long Range Research Aircraft) which operates in a broad partnership between German environmental and climate research institutes. Since 2012, the extensively modified Gulfstream G550 has been deployed on more than 20 research missions across five continents. HALO was procured from funds from the German Federal Ministry of Education and Research (BMBF), HGF (Helmholtz Association of German Research Centres) and the Max Planck Society (MPG). Operations are managed by the German Research Foundation (DFG), Forschungszentrum Jülich, Karlsruhe Institute of Technology (KIT) and Leibniz Institute for Tropospheric Research (TROPOS), Leipzig. DLR also owns and operates HALO.