Which of the following is NOT one of the common tiers in an EMS system?

In the context of an Emergency Medical Services (EMS) system, various tiers serve different roles in providing medical care and transport to patients. Each tier is designed to address specific types of emergencies and the level of care required.

First responders are usually the initial individuals to arrive at the scene of an emergency, such as police officers or firefighters, who may provide basic life support and stabilize patients until more advanced care arrives. Advanced Lifesaving (ALS) involves paramedics who can provide a higher level of medical care, including advanced medication administration and invasive procedures.

Air ambulance or aeromedical services are specialized operations that utilize helicopters or fixed-wing aircraft to transport critically ill or injured patients quickly, especially from remote locations or during time-sensitive situations.

Critical Care Transport, while very important in the overall continuum of care, is more of a specialized service that focuses on transporting patients who require highly specialized care beyond what is typically available in a standard ALS unit.

Therefore, when identifying a tier that is not commonly recognized as part of the traditional structure of an EMS system, Critical Care Transport fits that criteria. It represents a specialized category that does not encompass the foundational tiers typically noted in EMS operations.