sentences:  Examination of the aircraft's flight data recorder (FDR) revealed that shortly after the diversion occurred, the aircraft airspeed indicator began to fall to an alarmingly low indicated airspeed.Unbeknownst to the pilots, this was caused not directly, by a loss of power, but by ice formed inside the pitot tube, which reads the airspeed for the indicator by measuring the pressure of inflow air.The ice obstructing the pitot tube reduced the air inflow, thus giving an erroneously low indicated airspeed.