A good arguement for keeping your seatbelt fastened, regardless of whether or not the sign is lit! I was on a flight several years ago, approaching our destination so everyone was already buckled in with 'tray tables up'. The plane suddenly went nose down, banked hard left & dropped a couple thousand feet. Yes, my hearing has recovered. No thanks to the lady sitting beside me who decided to scream her head off, convinced that we were all going to die. It was not typical turbulence. Nor was it even close to a typical landing descent. I later learned that a private plane crossed too close & the TCAS kicked-in. Unfortunately, I never saw the other plane, so I can't say how close it looked.