Safety is critical, no margin for error. Situations are novel or unpredicable. Task is simple and job turnover is high. User lacks the reading, listening or visual skills to use a job aid. Users are unavailable or lack time for training.
Task is perceptual, unable to develop a useful job aid.
The three case studies below demonstrate application of these guidelines. The Pennsylvania EPA wanted to provide assistance and encouragement to farmers to recycle the solid waste produced on their farms by farm animals. Farmer Spreading Manure Manure contains nutrients that crops need, but the farmer needs to know how much manure his spreader is applying, then make the necessary adjustments to apply at the proper rate. This can vary depending on the crop type, manure type, spreader type and time of year. Calibrating the spreader is a relatively easy procedure, but is done only a couple of times a year.