I Dunno
I took a look at the Vermeer web site. A chipper in the photo on the site has a entry chute that is pretty big and the bottom of the chute is below waist height. Looks like it would be easy to get sucked in, if a big branch or tree section had a stub to catch an arm or hand. The photo shows an operator pushing in a tree trunk about 15" or so in diameter. Once the infeed takes hold of the branch, log or tree trunk, there is no hope. Some of these things have 200 HP, would not even slow down if a man went through.
You gents that operate a chipper similar to the one in the photo chime in and give us your take. I understand the red bar on the infeed area will stop the machine, but from the photo, looks as it could be difficult to operate if one is caught by a branch or stub. I guess if you are feeding branches or logs, you best feed butt first, so the "grabber" stubs won't grab.
PS, did a Google and found out the accident involving Brian Morse in Loveland CO occured on December 29, 2005. Is this the same incident of this topic?
For info, do a google on chipper accidents. Real scary, many folks have been killed in chipper accidents.