AIRBUS HELICOPTERS EC 130 near Halloran Springs, CA

Probable cause

The pilot’s decision to continue the visual flight rules flight into instrument meteorological conditions, which resulted in the pilot’s spatial disorientation and loss of control. Contributing to the accident was the company’s inadequate oversight of its safety management processes, including ensuring the pilots were accurately completing and updating the flight risk analysis, logging maintenance discrepancies, and ensuring the helicopter met Part 135 regulations before departure.

Contributing factors

Contributing to the accident was the company’s inadequate oversight of its safety management processes, including ensuring the pilots were accurately completing and updating the flight risk analysis, logging maintenance discrepancies, and ensuring the helicopter met Part 135 regulations before departure.

NTSB narrative

In preparation for the Part 135 on-demand charter flight, there was no record that the pilot or safety pilot obtained a formal preflight weather briefing for the accident flight either directly from a flight services provider, through the ForeFlight application, or from a third-party vendor. No data were available to determine what weather information the pilots may have accessed using the ForeFlight application or some other source. The flight risk analysis (FRA) form the pilot completed about 4 1/2 hours before the accident flight’s departure included risk items related to maintenance, weather, duty hours, and a second pilot. Based on the form’s risk scoring criteria, the pilot’s score of 12 for the accident flight was in the company’s low risk category (the maximum score for the flight to remain in the low risk category was 15). In the days preceding the accident, the helicopter had been undergoing routine maintenance that involved work on the radar altimeter, which was a required instrument for Part 135 flight operations. About 1727 on the day of the accident, the accident pilot and a company mechanic/pilot repositioned the helicopter from the maintenance facility to the company’s flight operations base, and during the flight the accident pilot noted the radar altimeter was not functioning. During the return flight, the pilot texted the director of maintenance (DOM) about the issue. After arriving at the company’s flight operations base, the pilot discussed the issue with the company flight follower (who was also the company’s president). According to the flight follower, who also held operational control of the charter flight, during the discussions he told the pilot that the flight could not depart if the radar altimeter was not functioning. A company mechanic performed some troubleshooting on the radar altimeter; however, he was unable to rectify the issue and the radar altimeter remained non- functional. The mechanic reported that the pilots and the DOM were aware that the radar altimeter was not functioning, yet they departed at 1822 on the positioning flight to pick up the passengers. About 40 minutes later, the positioning flight landed at the airport to pick up the charter passengers. After arrival, the pilot and flight follower had a phone conversation and exchanged text messages, but they did not discuss the status of the radar altimeter or weather conditions. The accident leg departure was delayed about 50 minutes due to a passenger’s lost passport. A review of surveillance video at the fixed-based operator showed the pilots in the lobby using their cellphones; it is not known if the pilots checked the weather on their cellphones during that departure delay. In addition, the pilot did not complete an update to the FRA (which was internet accessible) while waiting at the airport. There was no evidence that the radar altimeter began functioning normally before the accident flight. During the time between the pilot completing the FRA and the accident flight leg departure, the National Weather Service issued weather updates involving the planned flight route area. The updates included lower ceilings and precipitation with rain and snow showers across the region. The accident flight departed in dark night visual flight rules (VFR) conditions and no moon illumination with a planned route to follow freeways to the destination airport. The freeway lights, vehicle lights, and various ground lights along the route of flight would have provided the light sources for VFR orientation. ADS-B and company flight tracking data showed the helicopter following the freeways at various altitudes and airspeeds toward the destination airport. About 10 miles west of the accident site, with mainly freeway vehicle lights available, the pilot began operating the helicopter at lower and slower airspeeds, deviated to the north of the freeway about 3,100 ft laterally, then returned back over the freeway. The lower altitude, slower airspeed, and deviation were likely due to encountering low ceilings and reduced visibility related to precipitation. Generally, helicopter pilots are trained to slow down and descend, if prudent, when negotiating or encountering deteriorating weather conditions. This can allow a pilot more time to safely maneuver the helicopter to avoid the conditions. The accident site area included hilly terrain that was rising on both sides of the freeway and in front of the helicopter. About 2 minutes before the accident, the helicopter’s airspeed and altitude increased, with a slight deviation to the south of the freeway. It is unclear if the pilot was attempting an inadvertent instrument meteorological conditions (IIMC) recovery maneuver. The helicopter continued the right turn for about 10 seconds when the helicopter began a rapid descent into terrain while maintaining the right turn. Witnesses, who were traveling in their vehicles, reported observing a fireball to the south of the freeway. The witnesses reported that the weather conditions in the area were not good as it was raining with a snow mix. Search and rescue efforts were difficult due to weather conditions that included low visibility, rain, snow, and high winds. The helicopter wreckage, which was highly fragmented and not survivable, was located about 1 hour and 40 minutes after the accident. Postaccident examination of the airframe, engine, rotor blades, flight controls, rotor drive, main rotor, and fenestron components identified no evidence of preimpact malfunction or failure that would have precluded normal operation. The engine displayed rotational damage signatures and resolidified metal deposits consistent with powered operation at impact. All recovered instruments, avionics, and portable/personal electronic devices sustained damage that prevented data extraction. The helicopter wreckage was consistent with a high-energy, right-side-low attitude impact with terrain. The accident pilot was trained that, to recover from entry into instrument meteorological conditions (IMC), he should first level the wings on the artificial horizon indicator, maintain heading, adjust torque and airspeed for best rate of climb, and climb to an altitude that will avoid obstacles. The gradual right turn, increased airspeed, and increased descent rate were inconsistent with the training to recover from entry into IMC. The pilot may have been susceptible to the Coriolis illusion when maintaining a constant turn if he moved his head, for example, to look from inside the cockpit to outside the cockpit. In addition, the helicopter also began to accelerate as it descended, which could have resulted in a somatogravic (false climb) illusion that led the pilot to believe the helicopter was climbing. The pilot likely experienced spatial disorientation while maneuvering the helicopter in IMC, which led to his loss of helicopter control and the resulting collision with terrain. The accident occurred at 2208; while this time is not typically associated with extreme fatigue, it is a time when melatonin is increasing, and the body is preparing for sleep. Additionally, based on information from the pilot’s fiancée, the accident occurred during a time when the pilot would normally have been sleeping. Although the pilot had only been awake about 13 hours and on duty about 8 hours at the time of the accident, given the time of day and the body’s biological desire to sleep, the role of fatigue could not be ruled out. While the exact actions of the pilot before his spatial disorientation are unknown, fatigue has been shown to reduce one’s judgement, decrease reaction time, and degrade performance, all affecting the pilot’s ability to respond to deteriorating weather conditions. Recognizing that opportunities exist to identify hazards or deficiencies before an accident occurs is a vital component of the safety management system (SMS). However, Orbic Air missed several opportunities to ensure that the flight met Federal Aviation Regulations (FAR) Part 135.160 and was being operated in a safe manner. Based on information from the company mechanic, after performing unsuccessful maintenance troubleshooting, the flight departed on the Part 91 positioning leg with an inoperative radar altimeter. Following the performed maintenance, the inoperative radar altimeter was not entered into the aircraft maintenance log as required by the company’s general operations manual (GOM) by either the pilot who identified the discrepancy or the mechanic who performed the work to rectify the discrepancy. Company management (both the president and DOM) was aware of the radar altimeter’s status; however, they failed to exercise ground and flight operational control to cancel or modify the flight. In addition, the flight-follower had an opportunity to follow up with the pilot after the Part 91 positioning leg to ensure the radar altimeter was functioning, but neither the pilot nor flight follower readdressed the issue. Postaccident review of the FRA completed by the pilot about 4 1/2 hours before the accident flight showed concerns of accuracy related to risk items involving maintenance, weather, second pilot, and duty hours. Providing some leniency in the interpretation of the second pilot and borderline duty hours after experiencing the delay, a minimum rating of 18 should have been assigned to the flight, indicating an elevated risk that required a discussion with management and consideration of risk mitigation strategies. There was no evidence the pilot updated the FRA after his initial assessment.

Analysis

Primary failure mode: Spatial disorientation
First missed decision gate: Pilot should have aborted the flight due to radar altimeter issues and poor weather.

AIRBUS HELICOPTERS EC 130 near Halloran Springs, CA — 2024-02-10

Probable cause

Contributing factors

NTSB narrative

Analysis

NTSB coding

Evidence available

Docket documents39

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