The floats are inflated using gas stored in pressurised cylinders carried on board the helicopter.
During normal H-46 operations, hatches and windows are open and upon hard landings the lower plexiglass bubbles in the nose section frequently break.
The H-46 has very little buoyancy in the forward end which is an additional hazard when the aircraft rolls over and rapidly fills with water because the nose sinks first trapping personnel in the aft cabin.
Under these conditions of the aircraft rolling over, rapidly filling with water and sinking nosedown, expecially [sic] at night it is nearly impossible for occupants to detach themselves from seat belts and walk-around harness, swim down to the forward escape hatches and push them outward against inrushing water and egress successfully.
A study estimated 50% of those fatalities could have been prevented had the helicopters been equipped with adequate emergency flotation.