Air ambulance helicopter in flight. An air ambulance is a helicopter equipped with life- support systems and staff for emergency medical cases. It provides a rapid response to casualties in inaccessible locations, as it can perform vertical take-offs and landings in confined spaces. This is the Essex Air Ambulance. It serves the county of Essex in England. The helicopter is an EC135 Eurocopter and entered service in 2003. The skid undercarriage allows the helicopter to land on a variety of ground types and slopes.