The National Transportation Safety Board cites poor weather and “insufficient risk assessment” as causal factors in the February 2023 fatal crash of an air ambulance Pilatus PC-12/15 in Stagecoach, Nevada.
The pilot, two medical crewmembers, and two passengers were killed when the aircraft experienced a midflight breakup shortly after takeoff. The Pilatus was operating in night instrument meteorological conditions (IMC).
According to the 27-page NTSB final report released this week, the flight was a nonemergency transport of a patient from Reno-Tahoe International Airport (KRNO) to Salt Lake City International Airport (KSLC) in Utah.
The flight took off at approximately 9 p.m. MST. At the time of the accident the departure airport and surrounding area had been impacted by “significant winter weather” throughout the day, and the pilot who was on call for the operator earlier that day turned down a flight request due to low visibility, turbulence, and icing conditions.
It was noted that another medical operator that also flew the Pilatus PC-12 also turned down a request for a flight in the area due to the weather. The aircraft was equipped for flight in known icing conditions.
Risk Assessment Missing
The night of the takeoff the recorded weather conditions at the departure airport included visibility of less than 2 miles and a ceiling of 1,700 feet agl.
The flight crew, according to the NTSB report, was “relatively new in their respective roles.” The pilot had been with the company for approximately five months, and both the flight paramedic and flight nurse had been assigned to the airplane for about six months.
According to the air ambulance company’s website, the flight crews followed a protocol known as “three to say go, one to say no” as a best practice among air ambulance providers, meaning that any member of the flight team could raise a safety concern about the flight. It also noted that for rotorcraft flights the operator required that medical crew with less than one year of experience be paired with clinicians with more than one year as a means of enhancing safety. No such requirement was in place for fixed-wing operations.
The NTSB also said the operator’s procedures required company dispatchers to inform crews if a flight had been turned down by another operator due to weather conditions. However, the company communication logs reveal that did not happen the day of the accident.
The accident investigation determined that a flight risk assessment, which was required by the company before each mission, was not completed for the accident flight. The probe also revealed that the operator had another fatal accident 71 days before this accident, and the lack of a preflight risk assessment was a factor in that event as well.
The report of the February flight noted that “even if a risk assessment had been conducted, the crew’s relative inexperience, and lack of information about the earlier turndowns, increased the likelihood of a knowledge-based error during the risk-assessment and decision-making process. That an inexperienced flight crew was permitted to accept the accident flight given the weather conditions and the previous flight turndowns with no additional approval demonstrated an insufficient risk assessment process and lack of organizational oversight.”
The Flight
According to the NTSB report, the pilot contacted the KRNO ground control about 8:52 p.m. and was instructed to taxi to Runway 17L. Approximately a minute later, the ground controller observed the pilot was having difficulty exiting the ramp for the taxiway and warned them that the taxiway had not been plowed in a while. The controller advised the pilot to turn right when the aircraft went past the centerline of the taxiway.
The pilot subsequently received an IFR clearance to KSLC that included flying the ZEFFR7 standard instrument departure procedure from KRNO via the BLKJK transition. BLKJK is a GPS waypoint located about 20 nm east of the departure airport.
The pilot was cleared for takeoff, and ADS-B data shows the airplane climbing out about one minute later. The pilot acknowledged a frequency change to switch to Oakland Air Route Traffic Control Center and reported that he was climbing through 15,400 feet msl.
The controller instructed the pilot to climb and maintain FL 250 (25,000 feet msl) and cautioned him about light to moderate turbulence in the area. The pilot acknowledged the altitude assignment. No other radio transmissions were received from the pilot.
The aircraft continued climbing on a southeasterly heading until about 9:08 p.m. when it turned northeast in the vicinity of the WITTT waypoint. At approximately 9:11 p.m, the aircraft began a right turn prior to reaching the DATTT waypoint, which was the next waypoint along the departure procedure.
About this time, the airplane momentarily stopped climbing then resumed a climb to an altitude of about 18,300 feet msl for about 20 seconds. The ADS-B data indicates the airplane remained on this heading for about 47 seconds, climbing to about 19,000 feet msl before turning to a northeasterly heading.
The airplane continued on this heading and climbed to about 19,400 feet msl then at 9:13 p.m. entered a descending right turn at a rate of 1,800 feet per minute. The rate of turn continued to increase as the aircraft altitude decreased until ADS-B contact was lost at 9:14 p.m at an altitude of 11,100 feet msl in the vicinity of the accident site.
According to NTSB investigators, the pattern of the wreckage at the accident site was consistent with a low-altitude, in-flight breakup. Examination of the airframe and engine did not reveal evidence of mechanical malfunctions or failures with the engine, flight controls, or instruments that would have precluded normal operation. However, it was determined that the autopilot, which was engaged shortly after takeoff, was disengaged then reactivated at least twice during the short flight, then ultimately turned off.
Investigators reported that based on the evidence and the ADS-B track, it appears the pilot was attempting to hand-fly the aircraft and entered a graveyard spiral when he became disorientated while flying in night IMC, resulting in an in-flight breakup. Contributing to the accident was the disengagement of the autopilot for undetermined reasons, as well as the operator’s insufficient flight risk assessment process and lack of organizational oversight.
Additionally, the report stated an autopsy on the pilot discovered a brain tumor, which authorities said may have contributed to his loss of spatial orientation. But according to the pilot’s family, he was not exhibiting any symptoms and may have not been aware of the tumor’s existence.
