You see a fair few air ambulance operators through Boeing Field.  There are often flights moving people to and from the city from Alaska and other parts of the state.  The ones I am used to, though, tend to be older Learjets and US or Canadian registered.  We do get the occasional one from overseas, but I was quite surprised to get a G550 from China showing up as an air ambulance.  It seemed worthy of a look.  It was a pretty brief stop for the jet before it headed across the Pacific.  The naming seemed quite amusing – Happy Air!