Always probe with your weight on the back foot.
Gravity never takes a day (or a minute) off. When making those forays across a floor above a fire area, across the roof, or in any area where structural integrity is suspect, personnel should use a tool to probe ahead of them. Don’t, however, let this lead tool give you a false sense of security. When probing with a tool, consciously make an effort to keep your weight off the tool so that you will not fall if something gives way or you encounter a hole in the floor, or in the case of a roof, an unprotected shaft is present.
During hands-on training search operations at the Fire Department Instructors Conference in Indianapolis, we noticed that most firefighters do a good job of probing for floors, but they keep too much weight on the probing hand, foot, or tool. We had areas with floors missing and when the probing tool or body part found that area, the individual usually could not stop from falling forward into the missing floor as his forward momentum carried his body and the tool into the hole. We had to extricate more than a few surprised firefighters from these areas (they had a hood over their head for the evolution). Hopefully it was a lesson learned the hard way, but in a training session and not in the harder environment that is the fireground. Never trust what is in front of you without testing the area. Keep the weight off the leading foot or tool, and you will not experience a gravity-induced rapid downward movement.