Just got home from a cross Atlantic flight with USAir. Woman behinds suffered a stroke. We had to return to the airport. Luckily enough three doctors were aboard (although that is not really "luck" more the result of statistics. She could leave the plane walking, so I hope all went well.
A few years back, a passenger died over the ocean ad we traveled to Washington DC. The plane just continued on as the body rested on the floor in the back. Only later did I realize that the man ( I could only see his sports shoes) must have died - arriving at Dulles, an ambulance was waiting, but without lights, and no MD came on board. Instead, all passengers disembarked first.