The German Aerospace Center (DLR) and the Royal Netherlands Aerospace Centre (NLR) are two of the largest aerospace research and development organizations in Europe. Together they form the research alliance AT-One. DLR and NLR deliver innovative and independent Air Traffic Management research and implementation support with a focus on integrated simulation, verification and validation.

DLR and NLR have been actively participating in all phases of the Single European Sky ATM Research Programme (SESAR) research programme. DLR and NLR are both founding members of the SESAR 3 joining forces as AT-One alliance. The alliance operates from Amsterdam, Braunschweig and Brussels.