a single alouette iii helicopter, based at st. anthony central hospital in denver, colorado. in ontario, canada, the air ambulance program began in 1977, and featured a paramedic-based system of care, with the presence of physicians or nurses being relatively unusual. the system, operated by the ontario ministry of health, began with a single rotor-wing aircraft based in toronto. an important difference in the ontario program involved the emphasis of service. "on scene" calls were taken, although less commonly, and a great deal of the initial emphasis of the program was on the interfacility transfer of critical care patients. operating today through a private contractor (ornge), the system operates 33 aircraft stationed at 26 bases across the province, performing both interfacility transfers and on-scene responses in support of ground-based ems. today, across the world, the presence of civilian air ambulances has become commonplace and is seen as a much-needed support for ground-based ems systems. in other countries of europe, like sfr yugoslavia, first air ambulance appeared in the 1980s. the most of the fleet was previously used in military service. with the increased number of car accidents in 1979 on highways, the yugoslavian government made a decision to buy new or redistribution of use of old helicopters. organization air ambulance service, sometimes called aeromedical evacuation or simply medevac, is provided by a variety of different sources in different places in the world. there are a number of reasonable methods of differentiating types of air ambulance services. these include military/civilian models and services that are government-funded, fee-for-service, donated by a business enterprise, or funded by public donations. it may also be reasonable to differentiate between dedicated aircraft and those with multiple purposes and roles. finally, it is reasonable to differentiate by the type of aircraft used, including rotary-wing, fixed-wing, or very large aircraft. the military role in civilian air ambulance operations is described in the history section. each of the remaining models is explored separately. this information applies to air ambulance systems performing emergency service. in almost all jurisdictions, private aircraft charter companies provide non-emergency air ambulance service on a fee-for-service basis. government operated a eurocopter ec155b of the hong kong government flying service in some cases, governments provide air ambulance services, either directly or via a negotiated contract with a commercial service provider, such as an aircraft charter company. such services may focus on critical care patient transport, support ground-based ems on scenes, or may perform a combination of these roles. in almost all cases, the government provides guidelines to hospitals and ems systems to control operating costs—and may specify operating procedures in some level of detail to limit potential liability. however, the government almost always takes a 'hands-off' approach to the actual running of the system, relying instead on local managers with subject matter (physicians and aviation executives) expertise. ontario's ornge program and the polish lotnicze pogotowie ratunkowe (lpr) are examples of this type of operating system. the polish lpr is a national system covering the entire country and funded by the government through the ministry of health but run independently, there is no independent hems operator in poland. in north east ohio, including cleveland, the cuyahoga county-owned metrohealth medical center uses its metro life flight to transport patients to metro's level i trauma and burn unit. there are 5 helicopters for north east ohio and, in addition, metro life flight has one fixed-wing aircraft. in the united kingdom, the scottish ambulance service operates two helicopters and two fixed-wing aircraft twenty-four hours per day. multiple purpose in some jurisdictions, cost is a major consideration, and the presence of dedicated air ambulances is simply not practical. in these cases, the aircraft may be operated by another government or quasi-government agency and made available to ems for air ambulance service when required. in southern new south wales, australia, the helicopter that responds as an air ambulance is actually operated by the local hydroelectric utility, with the new south wales ambulance service providing paramedics, as required. in some cases, local ems provides the flight paramedic to the aircraft operator as-needed. in the case of the los angeles county fire department, the helicopters are brush fire choppers also configured as air ambulances with a paramedic provided from whichever fire department rescue unit has responded. sometimes the air ambulance may be run as a dual concern with another governmental body - for example, the wiltshire air ambulance was run as a joint ambulance service and police unit until 2014. in other cases, the paramedic staffs the aircraft full-time, but has a dual function. in the case of the maryland state police, for example, the flight paramedic is a serving state trooper whose job is to act as the observer officer on a police helicopter when not required for medical emergencies. fee-for-service in many cases, local jurisdictions do not charge for air ambulance service, particularly for emergency calls. however, the cost of providing air ambulance services is considerable and many, including government-run operations, charge for service. organizations such as service aircraft charter companies, hospitals, and some private-for-profit ems systems generally charge for service. within the european union, almost all air ambulance service is on a fee-for-service basis, except for systems that operate by private subscription. many jurisdictions have a mix of operation types. fee-for-service operators are generally responsible for their own organization but may have to meet government licensing requirements. rega of switzerland is an example of such a service. donated by business london's air ambulance md 900 in some cases, a local business or even a multi-national company may choose to fund local air ambulance service as a goodwill or public relations gesture. examples of this are common in the european union, where in london the virgin corporation previously donated to the helicopter emergency medical service, and in germany and the netherlands a large number of the 'christoph' air ambulance operations are actually funded by adac, germany's largest automobile club and drf luftrettung. in australia and new zealand, many air ambulance helicopter operations are sponsored by the westpac bank. in these cases, the operation may vary but is the result of a carefully negotiated agreement between government, ems, hospitals, and the donor. in most cases, while the sponsor receives advertising exposure in exchange for funding, they take a 'hands-off' approach to daily operations, relying instead on subject matter specialists. public donations mi-8amt ambulance helicopter in some cases, air ambulance services may be provided by means of voluntary charitable fundraising, as opposed to government funding, or they may receive limited government subsidy to supplement local donations. some countries, such as the u.k., use a mix of such systems. in scotland, the parliament has voted to fund air ambulance service directly, through the scottish ambulance service. in england and wales, however, the service is funded on a charitable basis via a number of local charities for each region covered. great strides have been made in the uk, with the 'association of air ambulance (aaa)'. this organization is widely credited for having created the political climate that made the helicopter industry and national health service recognise the enormous contribution charities make to trauma care in the united kingdom. in 2013, the aaa published the "framework for a high performing air ambulance service" which details many of the developments from 2008 to 2013. in recent years, the service has moved towards the physician-paramedic model of care. this has necessitated some charities commissioning clinical governance services, however many air ambulances operate under the tasking ambulances services clinical governance. the aaa now publishes best practice guidance on a range of operational and clinical functions and provides a code of conduct that all full members, both ambulance services and charities must uphold. "heavy-lift" a final area of distinction is the operation of large, generally fixed-wing air ambulances. in the past, the infrequency of civilian demand for such a service confined such operations to the military, which requires them to support overseas combat operations. military organizations capable of this type of specialized operation include the united states air force, the german luftwaffe, and the british royal air force. the swedish national air medevac - snam is an exception to the military only rule where the system is owned by the swedish civil contingencies agency myndigheten för samhällsskydd och beredskap and the 737-800 aircraft is provided under contract when so required by scandinavian airlines. each operates aircraft staffed by physicians, nurses, and corpsmen/technicians, and each can provide long-distance transport with full medical support to dozens of patients simultaneously. however, in recent years, exceptions to the "military-only" rule have grown with the need to quickly transport patients to facilities that provide higher levels of care or to repatriate individuals. air medical companies use both large and small fixed-wing aircraft configured to provide levels of care that can be found in trauma centres for individuals who subscribe to their own health insurance or affiliated travel insurance and protection plans. aircraft and flight crews in most jurisdictions, air ambulance pilots must have a great deal of experience in piloting their aircraft because the conditions of air ambulance flights are often more challenging than regular non-emergency flight services. after a spike in air ambulance crashes in the united states in the 1990s, the u.s. government and the commission on air medical transportation systems (camts) stepped up the accreditation and air ambulance flight requirements, ensuring that all pilots, personnel, and aircraft meet much higher standards than previously required. the resulting camts accreditation, which applies only in the united states, includes the requirement for an air ambulance company to own and operate its own aircraft. some air ambulance companies, realizing it is virtually impossible to have the correct medicalized aircraft for every mission, instead charter aircraft based on the mission-specific requirements. while in principle camts accreditation is voluntary, a number of government jurisdictions require companies providing medical transportation services to have camts accreditation to be licensed to operate. this is an increasing trend as state health services agencies address the issues surrounding the safety of emergency medical services flights. some examples are the states of colorado, new jersey, new mexico, utah, and washington. according to the rationale used to justify the state of washington's adoption of the accreditation requirements, requiring accreditation of air ambulance services provides assurance that the service meets national public safety standards. the accreditation is done by professionals who are qualified to determine air ambulance safety. in addition, compliance with accreditation standards is checked on a continual basis by the accrediting organization. accreditation standards are periodically revised to reflect the dynamic, changing environment of medical transport, with considerable input from all disciplines of the medical profession. other u.s. states require either camts accreditation or a demonstrated equivalent, such as rhode island, and texas, which has adopted camts' accreditation standards (sixth edition, october 2004) as its own. in texas, an operator not wishing to become camts accredited must submit to an equivalent survey by state auditors who are camts-trained. virginia and oklahoma have also adopted camts accreditation standards as their state licensing standards. while the original intent of camts was to provide an american standard, air ambulance services in a number of other countries, including three in canada and one in south africa, have voluntarily submitted themselves to camts accreditation. in the uk, the aaa has a code of conduct that binds one of the most regulated areas of operation together. it brings the fundraising standards board, caa / easa and the cqc together ensuring fundraising, air and clinical operations are in line with national regulation and best practice. the code goes further with an expectation of mutual support and working within its policy and best practice guides. medical control the nature of the air operation frequently determines the type of medical control required. in most cases, an air ambulance staffer is considerably more skilled than a typical paramedic, so medical control permits them to exercise more medical decision-making latitude. assessment skills tend to be considerably higher, and, particularly on inter-facility transfers, permit the inclusion of functions such as reading x-rays and interpretation of lab results. this allows for planning, consultation with supervising physicians, and issuing contingency orders in case they are required during flight. some systems operate almost entirely off-line, using protocols for almost all procedures and only resorting to on-line medical control when