By identifying accident causes and other uncertainties, an instructor can construct a series of scenarios that helps students learn everything - from estimating distances from a cloud to exercising good judgment - that's appropriate to the phase of training. The instructor should provide natural points throughout the scenario to ask the student to choose between "Should I continue?" "Should I divert? "or "Should I land?" Phases of flight where students may be asked to make the rantinue/divert/land decision might include: (1) before leaving the flight-planning room, (2) before takeoff, (3) hourly en route updates, (4) before initial descent and (5) before beginning approach. Perhaps the departure time is delayed while waiting for fuel, then the groundspeed is five knots slower than planned, then weather starts a slight deterioration, then there's a short ATC delay, add a small inconvenience with a nonessential cockpit technology failure and an impatient passenger, and you have all the ingredients for an accident chain.