Indeed, FEDEX was the original impetus behind such technology in a program named “Magic Window” which was intended to determine if real-time video of the runway, presented on a HUD, generated by a fog-penetrating sensor could be used to guide a pilot to a safe IMC landing. At the time, state of the art technology couldn’t provide a satisfactory picture. Persistent efforts and even an FAA research effort in the early 90’s demonstrated the capability. However, it was a long way from “ready for prime time”, then. The cost of a single night of diversions at Memphis was enough motivation for FEDEX to pursue a solution.
Early implementations of EVS on business jets used FLIR, which, at best, is of marginal benefit in fog. But it was enough for Gulfstream and technical partners to develop it into a certifiable system. In the last decade, there have been media accounts of multispectral EVS sensors that promised improved IMC performance. Meanwhile, rulemaking by EASA and the FAA has enabled operators certain operational benefits for IMC approach operations. The FAA even included EFVS, the operationally approved systems, as part of its NextGen technologies.