Great question Rudi! A good operator is taking some sort of action every 30-60 seconds for 4 hours to smokelessly destroy 20 to 30kg of waste. It's an extremely demanding task which requires intense focus -- so less time talking and more time doing. A focused operator will consume less biomass and pollute less when burning waste.
Here's how it integrates:
Training on Day 1 verbally introduces operating techniques and has them played out as drills. Allows for higher speed operation than the real thing, and thus more mistakes can be made and learned from. It also allows the instructor to demonstrate and test operators methodically for both classic operating scenarios and unusual ones.
Instruction Day 2 is verbally guided and practical. The muscle memory and basic concept from Day 1 get put to work under the pressure of keeping the incinerator running cleanly. Operators are highly alert and absorbing lots of information about the details of each operation, and the reasons for doing what when. The instructor is essentially running the incinerator though their hands initially, and then as operators master the basic patterns, verbal guidance shifts to problem solving.
Coaching on Day 3 is signal assisted and practical. Hand signals are introduced as part of the review of the previous day. The incinerator is started up, but this time, no operating instructions are given verbally -- only with hand signals. Operators quickly pick up the pace and build confidence.
Here are some benefits to using hand signals for the final day:
• Discretize the operations and provide an easy to remember intuitive standard terminology. One hand signal for 2-10 words.
• Puts instruction on it's own channel so it doesn't get droned out by other ambient conversations in between trainees and observers.
• Operators need to be able to ignore distraction and stay focused on the task, even while people are talking to them.
• Facilitates a transition from verbal to visual cues, since ultimately operators will be watching the system
• Operators can listen to the fire -- a bit like listening to an engine when driving instead of watching the RPM gauge on a car.
• Provides a medium in which the operator is still being guided, but not as strongly as with words. Operator is in control, hand signals prompt him for action when missed.
• Gives the instructor a chance to observe and evaluate performance on day 3. If after the first couple of hours, operators need almost no prompting, they can be certified.
• Can be easily picked up by in-country instructors, and stands less of a chance of deteriorating over time than verbal instructions.
• Bypasses language barriers. Operators are typically not literate and are often unaccustomed to hearing/interpreting western English/French. Reaction time is critical to keeping the incinerator operating in bounds.
• Operators are already struggling to read the analog temperature gauge (digital is worse), decide whether it's going up or down, and preparing to take the next step. Hand signals are less interruptive to their thought process than words.
• Allows other trainees to demonstrate their operating knowledge with instructional hand signals while the system is running, even if they aren't manning the incinerator. The alternative of 5-10 people telling the operator what to do next makes for unintelligible chaos.
• Avoids use of negatives (No, don't, not, stop etc) or critique when teaching on the final day of training, leaving the operator with a feeling of success, pride and competence after the training.
• Keeps the mood light and fun, which in turn imprints trainees with a positive association of the experience with the task that they need to perform.
• Instructor can multitask - coach operators with hands and have discussions with health workers at the same time.
• Is extremely effective in rapidly getting operators up the learning curve and performing professionally.