it. reporter: nothing could have prepared the passengers on united flight 1676, a nightmare at 34,000 feet, high above the rocky mountains. there was a lady behind me that was yelling, my baby, my baby. i can just assume she had an infant in her arms and let go of it. reporter: the plane carrying 114 passengers and five crew members encountered turbulence so rough that it plunged. it was instantaneous and everything that people had in their hands was flying through the air. people were screaming. reporter: according to the faa, 300 people have been injured because of turbulence between 2002-2011. air flows like water, and kit have interruptions in the flow. it can be caused by mountains,