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NTSB update on Atlas Air B767 crash: nose pitched down to about 49° ‘in response to elevator deflection’
12 March 2019

ADS-B track (source: NTSB)

Note: An earlier version of this article stated that the nose pitched down “in response to column input.” This was the exact phrasing used by the NTSB on their website. This phrasing was subsequently changed to “in response to nose-down elevator deflection” by the NTSB.

 

The NTSB issued an investigation update on the February 23, 2019, crash of Atlas Air flight 3591, a Boeing 767-375BCF that killed all three on board.  The aircraft entered a rapid descent from 6,000 ft and impacted a marshy bay area about 40 miles southeast of George Bush Intercontinental Airport (KIAH), Houston, Texas.

Air traffic control communications and radar data indicated the flight was normal from Miami to the Houston terminal area. About 12:30 pm the pilots contacted the Houston terminal radar approach control (TRACON) arrival controller and reported descending for runway 26L; the airplane was at 17,800 ft with a ground speed 320 knots. At 12:34, the airplane was descending through 13,800 ft, and the controller advised of an area of light to heavy precipitation along the flight route and that they could expect vectors around the weather.

About 12:35, the flight was transferred to the Houston TRACON final controller, and the pilot reported they had received the Houston Automatic Terminal Information System weather broadcast. The controller told the pilots to expect vectors to runway 26L and asked if they wanted to go to the west or north of the weather.

Radar data indicated the airplane continued the descent through 12,000 ft with a ground speed of 290 knots, consistent with the arrival procedure. The pilots responded that they wanted to go to the west of the area of precipitation. The controller advised that to do so, they would need to descend to 3,000 ft expeditiously.

About 12:37, the controller instructed the pilots to turn to a heading of 270°. Radar data indicated the airplane turned, and the automatic dependent surveillance-broadcast (ADS-B) data indicated a selected heading of 270°. The airplane was descending through 8,500 ft at this time.

About 12:38, the controller informed the pilots that they would be past the area of weather in about 18 miles, that they could expect a turn to the north for a base leg to the approach to runway 26L, and that weather was clear west of the precipitation area. The pilots responded, “sounds good” and “ok.” At this time, radar and ADS-B returns indicated the airplane levelled briefly at 6,200 ft and then began a slight climb to 6,300 ft.

Also, about this time, the FDR data indicated that some small vertical accelerations consistent with the airplane entering turbulence. Shortly after, when the airplane’s indicated airspeed was steady about 230 knots, the engines increased to maximum thrust, and the airplane pitch increased to about 4° nose up and then rapidly pitched nose down to about 49° in response to nose-down elevator deflection.  The stall warning (stick shaker) did not activate.

FDR, radar, and ADS-B data indicated that the airplane entered a rapid descent on a heading of 270°, reaching an airspeed of about 430 knots. A security camera video captured the airplane in a steep, generally wings-level attitude until impact with the swamp. FDR data indicated that the airplane gradually pitched up to about 20 degrees nose down during the descent.

 

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