Background
On December 15, 2022, about 2114 Hawaii-Aleutian standard time, a Raytheon Aircraft Company (formerly Beech) C90A, twin-engine, turbine-powered airplane, N13GZ, sustained substantial damage when it was involved in an accident near Kaupo, Hawaii. The airline transport pilot, flight paramedic, and flight nurse were fatally injured. The airplane was operated as a Title 14 CFR Part 91 air ambulance positioning flight by Guardian Flight LLC, doing business as Hawaii Life Flight.
Flight History
The flight departed Kahului Airport (OGG) on the Island of Maui, about 2053, on an instrument flight rules (IFR) flight plan, destined for Waimea-Kohala Airport (MUE) on the Island of Hawaii to pick up a patient. The pilot engaged the autopilot shortly after takeoff at about 160 ft msl, retracted the landing gear at about 700 ft above ground level, and reduced propeller pitch. After departure, the pilot contacted departure ATC, indicating the flight was at 1,000 ft msl climbing to 11,000 ft msl. The airplane initially proceeded north, then turned eastbound, consistent with the Onohi Two standard instrument departure procedure. As the airplane climbed through 1,400 ft msl, the pilot passed money to a medical flight crewmember seated in the cabin. About 2056, the pilot opened a music app on his cell phone and set it down in the right seat as the airplane climbed through 4,500 ft msl. The pilot looked at an approach plate on an iPad and entered approach frequencies.
Sequence of Events
About 2100, as the airplane climbed through 8,000 ft msl, the pilot repeatedly manipulated the buttons on the Collins MFD, but the screen remained blank and unresponsive. Review of previous flights revealed the Collins MFD was not working in the last four flights of recorded video. According to the Daily Maintenance Records, there were no entries for the MFD being inoperative in the two weeks prior to the accident. About 2102, the departure ATC specialist instructed the pilot to contact Honolulu Air Route Traffic Control Center (ARTCC). About 2103, the pilot contacted the ARTCC specialist and reported level at 11,000 ft msl, and requested the RNAV 4 instrument approach at MUE. About 2104, the ARTCC specialist asked if the pilot could climb to 13,000 ft msl, and the pilot responded that he could. The flight proceeded on an east-southeasterly heading along the northern shoreline of Maui, then turned southbound along the predetermined flight route.
About 2106, the autopilot disconnect alert tone sounded, and the autopilot disconnect light illuminated. The pilot’s Electric Attitude Director Indicator (EADI) did not display artificial horizon information for the duration of the flight; red warnings flashed several times and then remained lit. The flight nurse asked if the autopilot had disconnected, and the pilot confirmed. About 2107, the copilot side attitude indicator indicated a 30° bank angle to the right and then returned to level flight. The altimeter alert sounded at 13,220 ft. The pilot adjusted pitch trim, and the attitude indicator indicated a steepening right bank, then a left turn. Over the next several minutes, the airplane experienced erratic attitude indications and rapid descents. About 2112, the ARTCC specialist instructed the pilot to fly heading 180° and cleared the flight direct to TAMMI, the initial approach fix for the RNAV (GPS) 4 approach to MUE. The pilot acknowledged and selected direct TAMMI on the GPS. The attitude indicator then showed an increasing right bank, and the airplane descended at 1,000 ft per minute, accelerating to a rate of descent of 3,500 fpm. At 2113:40, the pilot reported, “Uhh, 13GZ is off navigation here… we’re gonna… we’re gonna give it a try.” The ARTCC specialist instructed the pilot to turn right to 170° and maintain 8,000 ft msl. The copilot attitude indicator displayed 90° angle of bank, and airspeed reached the maximum operating speed of 226 knots. At 2113:41, the attitude indicator showed an inverted descending right turn. At 2113:43, as the airplane passed through 7,700 ft msl, a final radio transmission believed to be from the pilot is heard saying “Hang on.” The altimeter showed very rapid descent; engine gauges were within normal range. At 2113:51, the airplane passed through 4,000 ft msl; the yoke moved quickly forward then aft, and a loud metallic bang was heard. The control panel illumination extinguished, consistent with main power bus failure and switching to battery power. The last recorded video and audio at 2114:06 showed the altimeter indicating about 400 ft msl. The pilot did not declare an emergency, report the instrumentation failure, or report that the autopilot was disengaged. ADS-B data stopped about 10 miles south of Kaupo, near where a witness observed the accident airplane impact the water.
A witness flying a Piper PA-44 from Hilo to Honolulu reported seeing the accident airplane well above and to the north. The witness watched the airplane as it began a right turn, then entered a spiraling right descending turn that steepened until impact with the water.
Personnel Information
The pilot held an Airline Transport Pilot certificate with multiengine land and rotorcraft-helicopter ratings, type ratings on the B-737, EMB-145, and LR-60, and a flight instructor certificate. He held a second-class medical certificate with a limitation for near vision. At the time of the accident, he was based at OGG. He had been hired by Hawaii Life Flight on December 2, 2019, with 7,668 total flight hours, about 950 in fixed-wing airplanes. His training record showed multiple unsatisfactory events, including failures in automation management, instrument use, and aircraft maneuvering. He had failed three of six checkrides on the first attempt. The Director of Operations noted concerns about the pilot's training record, indicating missed communication among management.
Aircraft Information
The Raytheon Aircraft Company C90A was manufactured in 2000, powered by two Pratt & Whitney Canada PT6A-21 engines. It was purchased by Guardian Flight LLC in September 2017. The aircraft was configured with two flight crew seats in the cockpit and patient stretcher systems in the cabin.
Meteorological Information
Dark night conditions prevailed; the moon was 38° below the horizon. Preflight planning reported VFR conditions with 10 miles visibility and the lowest clouds at 7,500 ft at the destination.
Wreckage and Impact Information
The airplane impacted the ocean off Maui and sank to a depth of about 6,420 ft. Wreckage was recovered on January 10, 2023. Examination revealed vertical crush damage consistent with high-rate descent impact. The empennage separated in flight and was not recovered. Control cable continuity was established for elevator and one rudder cable. The flaps were found in the UP position; the landing gear handle was in the DOWN position. The artificial horizon was uncaged and banked right and nose high. Engine examination showed no pre-impact mechanical malfunctions. The vertical gyro, common to both autopilot and attitude indicator, was examined; it showed inward crushing consistent with excessive external water pressure.