NASA Armstrong led the effort and have a decent little microsite describing the history with some videos of the testing: https://www.nasa.gov/offices/ipp/cente

NASA Armstrong led the effort and have a decent little microsite describing the history with some videos of the testing: https://www.nasa.gov/offices/ipp/centers/dfrc/technology/DRC-012-033-collision-avoidance.html#demonstrations https://www.nasa.gov/offices/ipp/centers/dfrc/technology/DRC... Essentially what you'd expect, in software then models then UAVs then full-scale planes with test pilots and finally roll-out to service aircraft.