The cabin crew announced that the plane was heading towards a spot of turbulence, and made the usual request for everyone to head back to their seats and buckle up.
Right after that announcement, a pre-recorded one was played in French, alerting passengers that the plane was going to make an emergency landing, telling them to pay close attention to their nearest emergency exit, and await instructions from the captain.
Needless to say, the combination of turbulence and the emergency warning message made the French passengers freak out. Some of them were crying, and it took the crew several minutes to realize their “mistake”.
The airline called it a very unusual occurrence, but I’ve actually encountered it myself – on several of my transatlantic flights, the crew started the wrong recording, and on one flight they even played the “brace brace brace” tape.
It shouldn’t be too hard for the crew to pick the correct recording from their list, but obviously, when humans are involved, things can go wrong.