I've experienced it three times. The first was in Albania when the Albanians were all seated in the back of the plane. They all burst out into applause as we taxied to the terminal. Guess they were glad to be home.
Next was when I took a flight from PVD to New York on Ransom Airlines. The way back was horrid. We had to get a jump start to even get the plane going. As we took off the engines caughed. Right. Caughed.
No heat in the darned plane, not even beverage service. Nasty November rain. I had a hangover. We all found religion on that flight.
The third time was, as another poster mentioned, a full brace landing. We'd left DFW to BOS and the flight returned to DFW after the landing gear refused to go up or go down. There really was a risk to that plane's safe landing yet I felt strangely calm throughout. But I did join in the applause when we came to a safe stop.
Rita