Not only do you need a spotter, the spotter had better be paying attention and know what he/she is doing.
I had an incident like this happen to me almost 20 years ago when maxing out on my bench press. My mistake for not using the guy who normally spots me, but this dude simply let go of the bar when it cleared the rack.
Weight didn't land on my throat because I managed to hold it up on one side, but the result put all the weigh on the other side, tearing my pectoral muscle.
Free weights are great for working out, but you have to be extremely cautious with certain exercises.