On March 12, 2019, the United States National Transportation Safety Board (NTSB) has issued investigative update on Atlas Air freighter crash in February 2019. The authority still refrains from providing accident causes, the update does reveal that the aircraft, it appears, entered turbulence shortly before the crash.
Atlas Air Boeing 767-375BCF, operating cargo flight 3591, crashed about 40 miles southeast of George Bush Intercontinental Airport (KIAH), Houston, Texas, on February 23, 2019. The were three people onboard ‒ two pilots and one jumpseat pilot ‒ none of whom survived.
Several witnesses and video footage captured on security cameras nearby saw the freighter enter a steep nosedive from approximately 6,000 ft. “I saw no evidence of aircraft trying to turn or pull up at the last minute,” NTSB chairman Robert L. Sumwalt has previously commented on the topic.
The flight, which took off from Miami International Airport (KMIA), Miami, Florida, was “normal” for the larger part of the journey, from Miami to the Houston terminal area, NTSB indicates.
ADS-B track, image: NTSB
Four minutes after pilots reported descending for runway 26L (at 17,800 ft with a ground speed 320 knots), the ATC advised them about light to heavy precipitation along the flight route and asked if they wanted to go to the west or north of the weather.
The pilots chose the first option, and as instructed, turned to a heading of 270° descending through 8,500 ft. As the aircraft had 18 miles left until passing the area of weather, the pilots were informed they could expect a turn to the north for a base leg to the approach to runway 26L. The weather was clear west of the precipitation area. “Sounds good” and “ok”, they responded. The aircraft levelled briefly at 6,200 ft and then began a slight climb to 6,300 ft.
“About this time, the FDR data indicated that some small vertical accelerations consistent with the airplane entering turbulence,” NTSB update indicates. “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. The airplane then pitched nose down over the next 18 seconds to about 49° in response to nose-down elevator deflection. The stall warning (stick shaker) did not activate”.
The airplane entered a rapid descent on a heading of 270°, reaching an airspeed of about 430 knots, indicates FDR, radar, and ADS-B data. This steep descent, lasting until the crash into the swamp, was also captured on security video camera nearby. “FDR data indicated that the airplane gradually pitched up to about 20 degrees nose down during the descent”.
The captain, who had worked for Atlas Air since 2015, had about 11,000 hours total flight experience with about 1,250 hours of experience in the Boeing 767. The first officer had worked for Atlas Air since July 2017 and had about 5,000 hours total flight experience with about 520 hours of experience in the Boeing 767.The Boeing 767-375 was manufactured in 1992 and converted to a freighter configuration in 2017. At the time of the accident it had 91,063 hours and 23,316 cycles.
Following the crash, debris was scattered in a marshy bay area, impeding the investigation. The board used airboats,barges, and amphibious equipment to recover the wreckage and flight recorders – a task which took 8 days to complete (CVR was found two days prior to FDR, on March 1, 2019).
“One engine and some landing gear components were found beyond the main debris field to the west,” NTSB clarifies. “Less dense components and a large portion of the cargo floated southward and were recovered up to 20 miles away. The wreckage was highly fragmented and resting in the soft mud in 1-3 ft of water”.