 Some systems operate almost entirely off-line, using protocols for almost all procedures and only resorting to on-line medical control when protocols have been exhausted.Some air ambulance operations have full-time, on-site medical directors with pertinent backgrounds (e.g., emergency medicine); others have medical directors who are only available by pager.For those systems operating on the Franco-German model, the physician is almost always physically present, and medical control is not an issue.