Cessna 340A accident near Santee, California, October 11, 2021

The NTSB's narrative final · quoted from the NTSB record

The pilot was on a cross-country flight, receiving vectors for an instrument approach while in instrument meteorological conditions (IMC). The approach controller instructed the pilot to descend to 2,800 ft mean sea level (msl) until established on the localizer, and subsequently cleared the flight for the instrument landing system (ILS) approach to runway 28R, then circle to land on runway 23. About 1 minute later, the controller told the pilot that it looked like the airplane was drifting right of course and asked him if he was correcting back on course. The pilot responded “correcting, 22G.” About 9 seconds later, the pilot transmitted “SoCal, is 22G, VFR runway 23” to which the controller told the pilot that the airplane was not tracking on the localizer and subsequently canceled the approach clearance and instructed the pilot to climb and maintain 3,000 ft. As the pilot acknowledged the altitude assignment, the controller issued a low altitude alert, and provided the minimum vectoring altitude in the area. The pilot acknowledged the controller’s instructions shortly after. At this time, recorded advanced dependent surveillance-broadcast (ADS-B) data showed the airplane on a northwesterly heading at an altitude of 2,400 ft msl. Over the course of the following 2 minutes, the controller issued multiple instructions for the pilot to climb to 4,000 ft, which the pilot acknowledged; however, ADS-B data showed that the airplane remained between 2,500 ft and 3,500 ft. The controller queried the pilot about his altitude and the pilot responded, “2,500 ft, 22G.” The controller subsequently issued a low altitude alert and advised the pilot to expedite the climb to 5,000 ft. No further communication was received from the pilot despite multiple queries from the controller. ADS-B data showed that the airplane had begun to climb and reached a maximum altitude of 3,500 ft before it began a descending right turn. The airplane remained in the right descending turn at a descent rate of about 5,000 ft per minute until the last recorded target at 900 ft msl, located about 1,333 ft northwest of the accident site. Recorded weather conditions at the pilot’s intended destination airport about 21 minutes before the accident showed that the cloud ceilings were broken at 2,127 ft msl, overcast at 3,227 ft msl. The closest weather reporting station to the accident site, which was about 1.8 miles south, showed a broken cloud layer at 3,086 ft msl. The airplane had undergone a conversion to modern avionics about 11 months before the accident. No reference to any additional training to the installed avionics was found within the provided pilot records. While the pilot had previous experience with other brands modern avionics, the investigation was unable to determine if the pilot had previous experience or training for the specific model of modern avionics installed in the airplane. The controller had cleared the flight to fly the ILS approach to runway 28R, circle to land on runway 23, and ADS-B track data showed that the airplane was about to be established on the localizer when it started to veer off course to the right, ultimately into an area with minimum vectoring altitudes that required the controller to issue instructions to the pilot to climb. During the divergence from the instrument approach, the airplane was at an altitude above the reported base of the broken cloud layer and below the base of the overcast layer at the destination airport, which most likely placed the airplane in and out of IMC conditions. Ultimately, the airplane climbed back into IMC conditions. It could not be determined if the pilot had inadvertently misconfigured the avionics for the instrument approach. Continuing the instrument approach would have afforded the pilot the opportunity to fly a stabilized approach in protected airspace and safely descend below the cloud layer prior to conducting the circle to land on runway 23. Given the airplane was maneuvering in IMC, it placed the pilot in conditions conducive to the development of spatial disorientation. The accident circumstances, including the tightening descending turn, and the subsequent high-energy impact, are consistent with the known effects of spatial disorientation. Additionally, examination of the airframe and engines revealed no evidence of any preexisting anomalies that would have precluded normal operation. Therefore, it is likely that the pilot was experiencing the effects of spatial disorientation when the accident occurred.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.