The Atlas Air Boeing 767 Freighter that crashed on February 23 on approach to Houston Intercontinental Airport entered its steep descent into Trinity Bay after encountering turbulence, followed by nose-down elevator deflection, according to an update issued by the U.S. National Transportation Safety Board Tuesday.
The report said data obtained from the aircraft's flight data recorder (FDR) and cockpit voice recorder (CVR) indicate Houston Approach control advised the crew of precipitation along their flight path as the aircraft descended normally through 12,000 feet mean sea level (msl) at a ground speed of 290 knots on the LINKK ONE arrival to the airport.
Following an ATC inquiry, the pilots asked to divert to the west around the weather. The controller responded that they “would need to descend to 3,000 feet expeditiously” to accommodate their request. ATC then instructed the crew to turn to 270 degrees heading while descending through 8,500 feet msl.
Approximately one minute later, controllers told the pilots to expect a northerly turn to a right base for Runway 26L after clearing the weather, which the pilots acknowledged with “sounds good” and “OK,” according to the NTSB. At around the same time, the FDR recorded "small vertical accelerations consistent with the aircraft entering turbulence."
Shortly thereafter, as the aircraft flew between 6,200 to 6,300 feet msl, "the engines increased to maximum thrust, and the airplane pitch increased to about 4 degrees nose up and then rapidly pitched nose-down to about 49 degrees in response to nose-down elevator deflection," although the stick shaker did not activate.
The aircraft then entered a steep descent along the 270-degree heading, reaching approximately 430 knots airspeed. The board added that, based on FDR data, the aircraft pitched up to an approximately 20 degrees nose-down attitude shortly before impact.
The NTSB released no further communications from the flight crew and noted that it would issue a full transcript when the public docket opens. The flight crew appeared fully qualified and current in the Boeing 767, the Board added.