Documents from the National Transportation Safety Board (NTSB) indicate the pilot of the helicopter that crashed in January, killing nine people including NBA legend Kobe Bryant, may have become disoriented in foggy conditions.
While federal investigators have not yet determined the cause of the crash, details found in a newly-released docket indicate that the pilot, Ara Zobayan, may have “misperceived” the helicopter’s position amid bad weather and not realized the craft was losing altitude.
Zobayan told air traffic control moments before the tragic accident that the helicopter was climbing, while it was actually descending, the NTSB documents indicate.
“During the final descent the pilot, responding to ATC [Air Traffic Control], stated that they were climbing to four thousand [feet],” wrote Marie Moler, NTSB Aircraft Performance Specialist, in one of the reports.
In adverse weather conditions, when a pilot is unable to use external visual cues and with insufficient attention to the helicopter’s instruments, he or she may become disoriented in a condition knows as “somatogravic illusion.”
“Without outside references or attention to the helicopter’s attitude display, the actual pitch and bank angles have the potential to be misperceived,” Moler wrote.
“Additional sensory inputs, such as visual cues, are needed to correctly perceive attitude and acceleration. When a pilot misperceives attitude and acceleration it is known as the ‘somatogravic illusion’ and can cause spatial disorientation,” she noted.
Although the helicopter’s accelerations were not recorded since the aircraft did not have a data recorder, Moler indicated that “[c]alculated apparent angles at this time show that the pilot could have misperceived both pitch and roll angles.”
Another of the reports notes that Zobayan, whose credentials include working as a flight instructor in Robinson and Schweizer helicopters, logged 8577 total hours of flight time, including 1250 hours on the Sikorsky S-76, the type of helicopter that he was piloting when on Jan. 26 it collided with hilly terrain near Calabasas, California, and was destroyed by impact forces and fire.
Toxicology tests performed by a forensic laboratory did not indicate the presence of alcohol and drugs in liver and muscle samples from the pilot.
A note in the medical and pathological information section of one of the reports stated that “[i]nsufficient blood specimen for analysis of carboxyhemoglobin was noted,” which is a test that would indicate the presence of carbon monoxide poisoning.
In a news release, NTSB said that no conclusions about how or why the crash occurred should be drawn from the information in the docket, which “does not provide the final report, nor does it contain analysis, findings, recommendations, or probable cause determinations.”
Nine people died in the crash, including Bryant’s 13-year-old daughter.