I will give a talk in two parts. In the first part I will discuss the science and engineering underlying the tools that are in use for air-ambulance operations with Ornge. I will not discuss methods in any detail if they are standard, but I will go into some detail on non-standard ideas. In the second part of the talk I will discuss some recent modeling efforts for land-ambulance modeling. I will discuss a method for obtaining a bound on the on-time performance that is achievable with a given fleet of ambulances. This method was created for analyzing a large (USD$250 million) contract for EMS (emergency medical service), and is useful for a range of EMS decisions. If time allows, I will also discuss some results associated with the fleet-mix question: should one use a fleet consisting only of advanced-life-support vehicles, or can a mixed fleet consisting of both advanced and basic life support vehicles deliver similar performance?