Duncan Aviation recently developed the Supplemental Type Certificates (STCs) and installation packages for Aviation Clean Air (ACA) ionization system for several aircraft. In response to the COVID-19 pandemic and for ease of flying of passengers, Duncan started this process in late 2020 and continued throughout 2021. They have so far developed STCs for Bombardier Global, Bombardier Challenger 300/350, Dassault Falcon 7X, and Dassault Falcon 2000/2000EX aircraft, with optional installation packages that include everything necessary for installing the ACA Ionizer system. In the last few months, Duncan Aviation partnered with Peregrine Avionics to develop STCs for the Gulfstream GIV and the Challenger 604. Duncan Aviation has developed ACA Ionizer installation packages for those two aircraft, as well.