CALSTAR was the first public nonprofit helicopter ambulance supported by a consortium of corporations and hospitals in the nation. CALSTAR's organizational model was developed to avoid the cost inefficiencies inherent in many hospital based helicopter ambulance programs. Helicopter ambulance programs operated by single hospitals invariably become loss leaders for those institutions with other patients subsidizing the revenue loss. CALSTAR was designed in anticipation of continuing cost containment trends in health care reimbursement that are impacting existing helicopter programs. As insurers have attempted to reduce payments for patient transportation by adopting more stringent medical necessity criteria, or capping payment rates, single hospital programs face termination, consolidation, or shared support relationships similar to CALSTAR.