next to the hull or seriously injured. you heard a big loud bang. i knew something bad was going on because the masks had come down. i had never experienced that before. reporter: the plane a new boeing 737 max 9. it made its first flight this past october and had been used by alaska airlines on only 150 trips. the federal aviation administration has temporarily grounded max 9s until alaska and united can make emergency inspections. we may look the at the manufacturer, the design of this aircraft, but we go where the evidence takes us. what is missing from the investigation is audio from the cockpit voice recorder, which was not recovered in time to stop its autothematic overwrite. gone are the recordings of the loud bang heard bypass engineers. its high time we improved the amount of data we get out of these voice recorders.