>Officials said the control tower recorded the Black Hawk helicopter flying at an altitude of 200 feet at the time of the collision, in line with its maximum allowed altitude for its flight path.
>However, data from the passenger jet’s flight recorder showed the collision occurred at an altitude of around 325 feet, plus or minus 25 feet.
If the tower and the Blackhawk were both indicating 200ft then this would suggest that the passenger plane had their altimeter set to the wrong barometric setting giving them a false reading.