From the FAA Remote Pilot study guide, but apparently referring to manned aircraft accidents: "...the vast majority of these accidents occur during landing (24.1 percent) and takeoff (23.4 percent)."
24.1 + 23.4 = 47.5, a minority, but this could still be a "vast majority" if there are a lot of small categories making up the majority of accidents. Assuming this sentence is not wrong, there must be at least three other categories, but for it to really be a "vast majority" more than three would be needed.
The only other category I can think of is cruise flight, but I'm not sure that would be considered a category rather than broken into more specific phases. What are some categories of accidents other than takeoff and landing?