You must not operate an ambulance when you are

Operating an ambulance requires a high level of physical and mental fitness. A qualified ambulance driver must be in optimal condition to ensure the safety of themselves, their crew, and the patients they are transporting. When a driver is permanently or temporarily disabled, they may lack the necessary capabilities to respond effectively to emergencies or operate the vehicle safely.

Additionally, driving while tired or sick can significantly impair judgment, reaction times, and overall performance. Fatigue can lead to slower responses and increased risk of accidents, while illness might affect concentration and decision-making abilities.

Thus, the summation of all these scenarios indicates that a driver must not operate the ambulance in any of these conditions to maintain safety and efficacy in emergency medical services. This collective reasoning supports the conclusion that all the mentioned conditions are grounds for not being fit to drive an ambulance.