The RALI project started in 1993, coordinated by J. Testud from CETP, J. Pelon from SA, and P. Flamant from LMD. In the early 2000, Alain Protat pursued the work which led to first RALI measurements. In 2010, Julien Delanoë took over the Pi-ship of the RALI project.
The year 2006 was clearly the «radar-lidar year» for our scientific community, with the launch of the first radar-lidar combination in space, consisting of the first 95 GHz radar in space, CloudSat (Stephens et al. 2002), and the CALIPSO dual-wavelength backscatter lidar (Winker et al, 2003), in the frame of the constellation of six satellites in formation for the monitoring of clouds, aerosols, and precipitation known as the «A-Train» (a NASA/CNES mission). RALI was therefore perfectly designed for validating A-Train measurements and cloud/aerosol products. In addition to that, RALI is great validation tool and can be used as a demonstrator and help to prepare future missions such as EarthCare scheduled for 2024 (Illingworth et al. 2015). RALI is currently the only airborne platform combining a HRS lidar at 355 nm and a multibeam 95 GHz Doppler cloud radar.