ERA20LA134

The pilot departed in the afternoon to complete a cross-country trip. He completed a brief stop at an intermediate airport, picked up a passenger, and then departed for the final destination under an instrument flight rules flight plan. The departure and en route phases of flight were routine and large portions of the pilot’s route were about 10 to 15 nautical miles from the shoreline over open water. About 1 hour into the flight, air traffic control instructed the pilot to proceed to an initial waypoint that was a part of a GPS instrument approach procedure at the destination airport; however, a descent clearance was not provided. About 13 minutes later, the airplane’s flight track showed a descending right turn spiral and radar contact was lost. No distress calls were received from the pilot. The wreckage was located on the ocean floor about 0.30 nautical mile from the last radar point and was not recovered. Photographs taken underwater revealed fragments of wing, fuselage, engine, propeller, and empennage in the same general area on the ocean floor. Although the engine was not examined, the propeller exhibited signatures that indicate the engine was producing power at the time of impact. Review of weather data and light conditions at the time of the accident revealed that the pilot was likely flying in instrument meteorological conditions (IMC) that were conducive to spatial disorientation; however, the pilot was current and qualified to operate the airplane at night in IMC. Although it is possible that the pilot experienced spatial disorientation and a subsequent loss of control, given that an autopsy, toxicology testing, and an examination of the wreckage could not be performed, the investigation was unable to determine the cause of the airplane’s turning descent into the water.

Spatial Disorientation The FAA Civil Aeromedical Institute's publication titled "Introduction to Aviation Physiology" defines spatial disorientation as a “loss of proper bearings” or a “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 instrument meteorological conditions (IMC), frequent transfer between visual meteorological conditions and IMC, and unperceived changes in aircraft attitude. The FAA's Airplane Flying Handbook (FAA-H-8083-3B) describes some hazards associated with flying when the ground or horizon are obscured. The handbook states, in part, the following: “The vestibular sense (motion sensing by the inner ear) can and will confuse the pilot. Because of inertia, the sensory areas of the inner ear cannot detect slight changes in airplane attitude, nor can they accurately sense attitude changes that occur at a uniform rate over a period of time. On the other hand, false sensations are often generated, leading the pilot to believe the attitude of the airplane has changed when in fact, it has not. These false sensations result in the pilot experiencing spatial disorientation.” The maintenance records for the airplane were not recovered. An airframe and powerplant mechanic reported that he completed an annual inspection on the accident airplane in August 2019. He did not possess a copy of his endorsement for the inspection; however, he did provide a billing invoice from the inspection. The mechanic reported that during the inspection the horizon attitude indicator was replaced with a “Century” instrument due to the accident pilot’s report that the old attitude indicator “was not acting correctly.” The mechanic added that no other components were replaced other than the brake pads and that he considered the accident airplane to be in “excellent condition.” On March 23, 2020, at 2103 eastern daylight time, a Maule MT-7-235 airplane, N899ZZ, was destroyed when it was involved in an accident in the Atlantic Ocean near Swansboro, North Carolina. The pilot and the passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. According to fuel transaction records and the manager of Orangeburg Municipal Airport (OGB), Orangeburg, South Carolina, the airplane and pilot were based at OGB. At 1820, the pilot added about 40 gallons of 100-low lead fuel to the accident airplane. Review of radar and flight track data provided by the Federal Aviation Administration (FAA) revealed that the pilot departed OGB at 1835 and subsequently landed at Mount Pleasant Regional Airport-Faison Field (LRO), Mount Pleasant, South Carolina at 1905. The pilot then filed an instrument flight rules flight plan and departed to Michael J. Smith Field Airport (MRH), Beaufort, North Carolina at 1950. During this stop-over, the pilot picked up the passenger. Thepilot was in contact with air traffic control (ATC) after he departed LRO, and radar data showed that the airplane climbed to 5,000 ft mean sea level (msl) and proceeded directly on course to MRH after takeoff. The route of flight was primarily over the Atlantic Ocean, and the course and altitude showed little deviation until about 2102, when the flight track showed a right turn to the southeast. The airplane continued in a rapidly descending right turning spiral until radar contact was lost. The last radar point at 2103:31 showed the airplane flying at 925 ft msl, 108 knots groundspeed, and on a 131° track. Review of ATC communications provided by the Marine Corps Air Station Cherry Point, North Carolina, revealed that the pilot’s communications were routine until radar contact was lost. About 2048, the pilot checked in with Cherry Point ATC at 5,000 ft, reported he had the weather at MRH, and requested the RNAV 26 instrument approach procedure. The pilot was told to expect the RNAV approach, and, about 2050, the pilot was instructed to fly direct to CIGOR, which was a GPS waypoint on the RNAV 26 approach. The pilot acknowledged the instructions by stating “proceed direct.” No further communications were received from the pilot. ATC attempted to reach the pilot several times after radar contact was lost; however, no response was received. According to the US Coast Guard (USCG) mission coordinator, they were informed about 2130 that an airplane was reported missing over the water. They initiated a search and rescue mission, and, at 2335, small fragments of airplane debris and personal effects were located at the surface of the ocean about 1.55 nm southeast of the last radar point. Several days after the accident, the main wreckage was located by a private diving company about 0.30 nautical mile from the last radar point at the bottom of the ocean floor. Figures 1 and 2 provide an overview of the final minutes of the flight track data (as represented by the red line), the location of the main wreckage, and the USCG located debris. Figure 1: Overview of the final minutes of the flight track. Figure 2: Closer view of the final few minutes of flight track data. An autopsy and toxicology testing were not performed. According to an NTSB weather study, an overcast layer of clouds was likely present around the accident site and flightpath. The accident occurred more than 1 hour after the end of civil twilight, and the moon was set at the time of the accident. The nearest weather observation facility was Bogue Field Marine Corps Auxiliary Field (NJM), located 16 miles north of the accident site, at an elevation of 21 feet. The NJM weather at 2057 recorded wind from 220° at 4 knots, 10 miles visibility or greater, overcast ceiling at 1,700 ft above ground level (agl), temperature of 16°Celsius (C), dew point temperature of 13°C, and an altimeter setting of 30.12 inches of mercury (inHg). According to the flight crew of the USCG aircraft that supported thesearch and rescue, when near the debris about 2345, they observed an overcast ceiling of 1,400 ft, visibility 10 miles, wind 290° at 10 knots, and a wave height of 4 ft. Leidos Flight Service found that, at 1822, the accident pilot requested standard weather briefings through a third-party provider. The weather briefings received contained all the standard information valid at that time, including, AIRMETs, METARs, terminal aerodrome forecasts, and pilot reports for the two intended flights that evening; the possibility for overcast ceilings along the pilot’s route and at the destination was documented in the briefing. Review of the pilot’s electronic logbook found that he had logged a total of 591 flight hours, of which 450 hours were in the accident airplane. He had logged a total of 91 hours of instrument time, of which 49 hours were in instrument meteorological conditions (IMC), and 15.8 of the IMC flight hours were logged in the preceding 90 days. He had logged 11 instrument approaches in the preceding 6 months. He logged 86 total hours of night flight, of which 21 hours were within the preceding 90 days. Photographs of the wreckage taken by a diver working for a private company revealed fragments of the fuselage, a wing, and empennage in the same general area. The engine and propeller were found about 10 ft from the main wreckage. The engine had separated from the firewall, and the propeller had separated from the engine. The propeller exhibited s-bending and torsional twisting. No components of the engine or airframe had been recovered by the completion of the NTSB’s investigation.