Prior to emplaning for any descent, the sky gods will be given, from the PJI, a DZ brief and then a brief on all phases of the jump which include the do's and don't when being hung up and a HUPRA being deployed.
The main point being emphasized is you DO NOT pull the reserve. If you do, it would probably cause the aircraft to stall and so the pilots, switiching to survival mode, would apply full power to keep the aircraft flying.
The deployment of the reserve would cause either
1. The aircraft to potentially stall and so the command to cut the cable regardless of wheter HUPRA has been attached or not will be given.
2. The deployed reserve parachute to be ripped from the harness.
3. The harness itself tearing apart .
4. Or the static line detaching from the main parachute.
If this causes the main chute to be deployed then the parachutist would be a very lucky guy otherwise he'd be enjoying his first and most probably his last free fall jump.
The "hands on the head" is more to keep your hands away from the red handle rather than indicate you are okay. You can wave or give the thumbs up if you want to.
The aircraft will then climb to a safe height, do a gentle turn on the side the parachutists is hung up on to stop them from bouncing and denting the side of the aircraft and then the cable is cut!
Then I guess the big paperwork moutain will appear!
CF.