sharkmasterbc once bubbled...
The reason I have asked this question is because I had an argument with another Padi Pro. not too long ago and for some reason he/she took the stand that you should hold the student on the bottom...I totally disagreed but was just curious as to what others thought.
I have had this happen to me numerous times and I always try and slow the "bolters" ascent to a safe rate. Once we reach the surface then I try to calm the person down and see if they want to try again. I think by holding someone down you will prob make the panic worse and that person will probably never get into the water with you again for fear of being held underwater...
I have watched an instructor hold a student down, when I was a D/M. The instructor got control of the student, got the student to put the reg back into her mouth, got her to start breathing properly, then took her to the surface gently. Needless to say getting her to put her mask back on at depth was probably out of the question at this time. She held it in her hand as she ascended, and never once tried to put it back on herself.
Now that I teach, I make good and sure that the students spend a lot of time in the 4 ft shallow end of the pool practicing mask clearing and regulator purging, so that they will not be inclined to panic in the deep end of the pool nor in the 15 to 20 ft depth of the open water where we perform these drills.
I have never had a problem myself with students bolting. I believe it is because I spend a lot of time with them shallow first. Prophylaxis early trumps prophylaxis late every time.
You never know when a student is going to panic however. The signs are sometimes there and sometimes not. Maybe they are having a bad day, and the cumulative weight of their personal life plus the drive in traffic to the dive site plus what to them is task loading on scuba has gotten to them.
Having said all that, I was taught in my ITC that if a student is holding their breath, you cannot let them ascend to the surface from any depth. And if they are breathing properly, you should not prevent them from going up. You may have been taught differently. I watch for bubbles.
Hope that answers your question. You will need to confer with your course director and re-read your instructor standards to answer this question specifically for yourself (PADI). Sounds like there is some doubt in your mind, and there should not be.