What is level-4 flight?
There are four types or "levels" of drone flights under Japanese regulations. Level 1 is where the human pilot stays within visual range of the aircraft. These flights are typically for things like aerial photography and bridge inspections. Level-2 flights are automated, with a programmed departure, speed, route and arrival that takes place within visual range. These flights are often conducted to spray crops or to survey land for civil engineering projects. Level-3 flights are "out-of-sight flights over uninhabited areas." They are permitted in places where humans are not usually present, such as over rivers, the ocean or forests. Test flights conducted by Japan Post for transport between post offices in Fukushima prefecture, in northern Japan, fall into this category.