The NTSB has released its findings on Atlas Air 5Y3591, a 767 freighter flight that crashed on approach to Houston (IAH) in February last year. The release comes ahead of a final report which is expected within the next few weeks. In the immediate aftermath of the crash, observers were perplexed and alarmed at the sudden and steep descent the 767 appeared to have experienced as it was performing an otherwise relatively normal approach. The aircraft in question was Boeing 767-375(ER)(BCF) registered N1217A. ADS-B data from the flight can be found here.

The findings indicate the cause of the crash was disorientation on the part of the first officer. However, the NTSB also points to the captain’s failure to properly monitor the situation, as well as failings in industry standards for performance assessment that failed to catch “aptitude related deficiencies and maladaptive stress response” on the part of the first officer. As is often the case, it was a sequence of failings that led to the deaths of captain, first officer, and an additional pilot in the jumpseat.

However, at the heart of the sequence of events that led the 767 freighter to rapidly descend into the ground was what is known as a “pitch-up somatogravic illusion,” a phenomenon in which an increase in acceleration can create the illusion that the aircraft is pitching up. That happened as a result of the go-around mode being activated inadvertently. The first officer evidently believed the aircraft was stalling despite no stall warning activating in the flight deck.

The NTSB released the following animation of the flight:

The captain was also distracted because he was setting up the approach and speaking to ATC, according to the NTSB, which said “his attention was diverted from monitoring the airplane’s state and verifying that the flight was proceeding as planned. This delayed his recognition of, and his response to, the first officer’s unexpected actions that placed the plane in a dive. Investigators also concluded the captain’s failure to command a positive transfer of control of the airplane as soon as he attempted to intervene on the controls enabled the first officer to continue to force the airplane into a steepening dive.”

On top of that, investigators found that the first officer had performance deficiencies which he took deliberate steps to conceal, and might have led Atlas Air to take appropriate action had they known of them in the first place.

“The first officer in this accident deliberately concealed his history of performance deficiencies, which limited Atlas Air’s ability to fully evaluate his aptitude and competency as a pilot,” said NTSB Chairman Robert Sumwalt. “Therefore, today we are recommending that the pilot records database include all background information necessary for a complete evaluation of a pilot’s competency and proficiency.”

As a result of the investigation, the NTSB has issued six new safety recommendations to the FAA, addressing “flight crew performance, industry pilot hiring process deficiencies, and adaptations of automatic ground collision avoidance system technology.”

Featured image © Jehu Monterroso