Never experienced this in 25 years of flying. I do know of two incidents involving colleagues, one that was terminally ill and was flying back to the US from Singapore and died on the plane. The second was another colleague who was flying from Brasil to DC and a gentleman died of a massive heart attach about 2 hours into the totally full flight so the put the body into a lavatory for the duration. Obviously these events are always tragic but I can't imagine how hard this must be on the cabin crews. No training could possibly be adequate.