According to Norminn :
Just in the past week or so, there was a guy killed mowing near a pond
in a park. Mower rolled over into the pond with him under it. All one
needs on a hill is a soft spot of ground, even without steep incline, to
roll it over.

My brother is a writer for the Ontario Ministry of Environment (press
releases etc). He told me that tractor rollovers or flips is one of
the largest causes of death or major injury short of road accidents.
While some of that is related to farm tractors rather than yard/lawn
tractors, the stats for those are pretty high on their own.

Our Cadet is very heavy, holds slopes pretty well, and most of
our property is pretty flat. But there's a couple of places
where we use a weedwacker instead.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.