I've ridden this ride many times and yes, there is nothing scarier than IOA than P-flyers in the rain!
There are a number of safety devices used on the ride:
1) Seat Belt. Everyone who rides this ride is required to use the seat belt. This seat belt is locked in and CAN NOT be released by the rider. The locking mechanism is electric and can only be released using the bus bar in the load station.
2) A pull-down lap bar. This is similar to the lap bars that are used on swing rides at many other theme parks and carnivals. It doesn't lock, but rather slides down the supports for the seat and is used as a secondary safety measure.
3) Finally, a second seat belt for small children. For added safety, a second seat belt is used for smaller children. This seat belt basically wraps around one of the child's thighs. Trust me, with this seat belt in place (plus the other 2 safety devices listed above), there is no way for ANYONE to get out of that seat during the ride.
Again, although somewhat frightening given the ride's height and speed, it is VERY VERY safe for anyone meeting the minimum height requirement.