HISTORY OF FLIGHTOn March 13, 2020, about 1447 Pacific daylight time, a Mooney M20K, N777WP, was substantially damaged when it was involved in an accident near Sylmar, California. The private pilot and passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The cross-country flight departed Soutwest Oregon Regional Airport (OTH), Oregon, about 1040 and was destined for Van Nuys Airport (VNY), California. Review of automatic dependent surveillance-broadcast (ADS-B) data and air traffic control communications between the pilot and the Van Nuys Air Traffic Control Tower controller revealed that, the pilot initially advised the controller he was inbound on the instrument landing system (ILS) at 1443:22. The airplane was aligned on the localizer course to runway 16R at that time (see figure 1). Between 1443:24 and 1444:39, the track shifted right and left of the localizer course, while descending from 4,281 ft mean sea level (msl) to 3,563 ft msl. The controller cleared the pilot to land on runway 16R, and reported wind from 140°, at 7 knots. At 1444:44, the data showed that while in the vicinity of the final approach fix, a right turn to a west-southwesterly heading, until 1445:02, when a left turn to southerly heading was made, at an altitude of 3,163 ft msl. At 1445:02, the controller queried the pilot, advising them they were deviating to the west and at a low altitude, to which the pilot responded they were on course and level. About 14 seconds later, the data showed a right turn to a westerly heading at an altitude of 3,419 ft msl. About 4 seconds later, the controller alerted the pilot that they were right of. The pilot responded shortly after that they were turning. At 1445:54, the controller issued the pilot instructions to fly heading 160°, climb and maintain 5,000 ft, to which the pilot acknowledged the altitude only. The controller responded to the pilot’s acknowledgement and instructed to the pilot to fly a 160° heading and climb to 5,000 ft, which the pilot acknowledged the altitude only a second time. About 2 seconds later, the controller asked the pilot to ensure they were on a 160° heading, which went unanswered by the pilot. About 7 seconds later the controller repeated that they need to climb to 5,000 ft, and a 160° heading. At 1446:30 the pilot replied “copy, 7WP.” Despite further attempts, no further radio communication acknowledging the controller’s instructions was received from the pilot. At 1446: 45, the data showed a right turn to a southerly heading, at an altitude of 3,106 ft msl. The airplane continued on a southerly heading until 1447:03, when a right 270° turn was observed. Throughout the turn, altitude fluctuated between 2,288 ft msl and 2,700 ft msl. The last recorded radar target was at 1447:14, at an altitude of 2,638 ft msl, within the vicinity of the accident site. Figure 1: Radar Data Overlay over ILS Runway 16R -Z Approach Plate PERSONNEL INFORMATIONThe pilot’s most recent logbook was not located during the investigation. However, on an insurance application, dated February 5, 2020, the pilot reported he had accumulated 4,594 hours total flight time, of which 3,560 hours were in the accident make/model airplane. It could not be determined how much instrument flight time the pilot had accumulated, or if the pilot had maintained their instrument proficiency. METEOROLOGICAL INFORMATIONAt 1451, the automated weather observation station at Van Nuys Airport, Van Nuys, California, located about 8.5 miles south of the accident site reported wind from 160° at 6 knots, visibility 10 statute miles, few clouds at 700 ft, scattered cloud layer at 1,100 ft, overcast cloud layer at 1,800 ft, temperature 12°C, dew point 11°C, and an altimeter setting of 29.92 inches of mercury. At 1456, an Aviation Selected Special Weather Report (SPECI) was issued at VNY, reporting, wind from 150° at 4 knots, visibility 7 statute miles, broken cloud layer at 900 ft, overcast cloud layer at 1,800 ft, temperature 13°C, dew point 11°C, and an altimeter setting of 29.92 inches of mercury. About 20 minutes prior to the accident, pilot reports indicated that cloud tops varied from 7,500 ft to 5,500 ft mean sea level over the Burbank and Los Angeles areas. WRECKAGE AND IMPACT INFORMATIONExamination of the accident site revealed that the airplane impacted power lines, which were about 50 ft in height, on a heading of about 064° before impacting terrain about 250 ft east and downslope of the powerlines. The fuselage came to rest inverted on heading of about 014° magnetic in a canyon surrounded by mountainous tree covered terrain, at an elevation of about 2,315 ft mean sea level (msl). The wreckage debris path was measured about 260 ft in length, oriented on a heading of about 064° magnetic and contained all major structural components of the airplane. Examination of the recovered wreckage established flight control continuity was able to be established from the cockpit to all primary flight controls. Numerous separations were noted within the control system and were found consistent with being cut by wreckage recovery personnel or they exhibited signatures consistent with overload separation. No evidence of any preexisting mechanical malfunction with the airframe or engine, including the vacuum system were found that would have precluded normal operation. ADDITIONAL INFORMATIONThe FAA Civil Aeromedical Institute's publication, "Introduction to Aviation Physiology," defines spatial disorientation as a “loss of proper bearings; state of mental confusion as to position, location, or movement relative to the position of the earth.” Factors contributing to spatial disorientation include changes in acceleration, flight in IFR conditions, frequent transfer between visual flight rules and IFR conditions, and unperceived changes in aircraft attitude.