Jumpmasters have an ambiguous situation during the time a student realizes it's pull time and when he starts to pull. Jumpmasters must allow a student to learn and not overreact. This method requires jumpmasters to read a student's actions. Both methods are widely used and work. Good students will be successful with either method.
Unaware students are the ones of concern.
The off in the ozone student is the one who doesn't do anything except look around . He doesn't perform tasks or respond to in-flight commands at the top end of the dive. This tips off the jumpmasters to know that this student needs an early pull signal. Even then, he may not pull. JM1 anticipates pulling the student's ripcord.