N515GK

HISTORY OF FLIGHTOn October 18, 2022, at 0709 eastern daylight time, a Beech E-90, N515GK, was substantially damaged when it was involved in an accident in Marietta, Ohio. The two commercial pilots were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 135 positioning flight.

The flight originated at the John Glenn Columbus International Airport (CMH), Columbus, Ohio, about 0640 and was enroute to Mid-Ohio Valley Regional Airport (PKB), Parkersburg, West Virginia. Automatic dependent surveillance - broadcast (ADS-B) data revealed that after takeoff from CMH the airplane climbed and turned on a ground track of 115°, and then leveled off at 11,000 ft mean sea level (msl), where it remained for most of the enroute portion of the 75-nautical-mile (nm) flight.

Air traffic control (ATC) communication information revealed that the flight crew was in communication with the Indianapolis Air Route Traffic Control Center during the enroute portion the flight and that all communications with the controllers were normal with no indication of any irregularities.

After departing the cruise portion of the flight, in preparation for the approach into PKB, the airplane descended at a rate of about 1,200 ft per minute at a calculated airspeed of 122 knots. As the airplane approached PKB, the controllers cleared the flight to descend and maintain 4,000 ft msl.

About 0706, the pilot contacted PKB requesting the RNAV approach to runway 21 and was instructed to report upon reaching MIDCO, the Final Approach Fix (FAF) for that instrument approach. MIDCO was 5.9 nm from the runway threshold and had a minimum crossing altitude of 2,800 ft msl. The pilots were subsequently cleared for the RNAV RWY 21 approach. The airplane leveled off at 2,800 ft msl and increased speed to 150 knots and turned on a long final approach to join the RNAV RWY 21 instrument approach procedure. Shortly after, the pilots were instructed to contact the PKB control tower. Subsequent communication exchanges with the controllers were normal.

Figure 1 - Airplane flight path with selected times and altitudes annotated. A portion of the RNAV (GPS) RWY 21 instrument approach procedure has been superimposed onto aerial imagery.

About 0709, as the airplane was on a 3-mile final approach, the controller notified the pilots that there was a vehicle on the runway checking for wildlife and that it would be cleared shortly; this was acknowledged by the pilots. About 1 minute later, the airplane was observed emerging from the overcast cloud layer while it simultaneously crossed MIDCO, after which the pilots were cleared to land on runway 21. It was traveling about 170 knots and aligned with the runway heading. The speed decreased to 126 knots in preparation for approach and landing. (The airplane’s published approach speed was about 90 knots and the stall speed was about 65 knots with full flaps [88 knots with no flaps at maximum gross weight]). There were no additional communications received from the flight crew.

Multiple eyewitnesses located on the airport and area surrounding the accident site reported that the airplane, while flying straight and level, suddenly began a steep descent and spun near vertically to the ground. Security camera footage from multiple camera angles showed the airplane’s descent through impact, which was consistent with the eyewitness’s accounts (see figure 2).

Figure 2 - Three sequential still images from the security camera video showing the airplane’s near vertical descent to impact. Note landing light and position light. AIRCRAFT INFORMATIONThe airplane was a high-performance, conventional-tail, pressurized, twin-engine turbo-propeller airplane and was designed and equipped for flight in instrument meteorological conditions, day or night, and into known or forecast icing conditions. The surface deice system would remove ice accumulation from the leading edges of the wings and stabilizers through the use of pneumatic boots. Ice would be removed by alternately inflating and deflating the deice boots. Pressure-regulated bleed air from the engines supplied pressure to inflate the boots. A venturi ejector, operated by bleed air, created a vacuum to deflate the boots and hold them down while not in use. To assure operation of the system in the event of failure of one engine, a check valve was incorporated in the bleed air line from each engine to prevent loss of pressure through the compressor of the inoperative engine. Inflation and deflation phases were controlled by a distributor valve. A three-position switch in the ICE PROTECTION group on the pilot's subpanel, placarded SURFACE DEICE - SINGLE - OFF MANUAL, controlled the deicing operation.

The switch was spring-loaded to return to the OFF position from SINGLE or MANUAL. When the SINGLE position was selected, the distributor valve would inflate all of the airframe boots, both wings and tail. After an inflation period of approximately 7 seconds, an electronic timer switched the distributor to deflate the boots. After these boots have inflated and deflated, the cycle was complete. When the switch was held in the MANUAL position, all the boots would inflate simultaneously and remain inflated until the switch was released. The switch returned to the OFF position when released. After the cycle, the boots would remain in the vacuum hold-down condition until again actuated by the switch.

According to the airplane’s Airplane Flight Manual (AFM) landing checklist:

Figure 3 - Excerpt from AFM showing the landing checklist items. METEOROLOGICAL INFORMATIONWeather information at the time of the accident indicated that there were pilot reports throughout the area for trace to moderate icing conditions and AIRMETs for moderate icing. Weather satellite data showed supercooled liquid water clouds from 1,300 ft above ground level (agl) to about 8,000 ft agl.

Mid-Ohio Valley Regional Airport (PKB), Parkersburg, West Virginia, had the closest official weather station to the accident site and was the intended destination airport. PKB had an Automated Surface Observing System (ASOS) and reports that were augmented by ATC. The PKB ASOS was located 4 miles south-southwest of the accident site at an elevation of 808 ft and issued the following observations surrounding the period of the accident. The PKB reported weather at 0653 included wind from 260° at 3 knots, visibility 10 miles or greater, overcast ceiling at 1,400 ft agl, temperature of 3° C, dew point temperature 1°C, and an altimeter setting of 29.80 inches of mercury. The sea level pressure was 1009.4 hPa, temperature 3.3°C, and dew point temperature 0.6°C.

The reported weather at PKB at 0750 included wind from 260° at 6 knots, visibility 10 miles or greater, overcast ceiling at 1,300 ft agl, temperature of 3°C, dew point temperature 1°C, and an altimeter setting of 29.81 inches of mercury.

The NWS Current Icing Product (CIP) and Forecast Icing Product (FIP) were intended to supplement other icing advisories such as AIRMETs and SIGMETs. The CIP icing probabilities and severity and 1-hour forecast was valid at 0700 and showed that at 3,000, 4,000, and 5,000 ft, there was a 60 to 85% probability of icing at 3,000 to 5,000 ft surrounding the accident area (see figure 4). Furthermore, the icing intensity near the accident site ranged from “light” to “heavy,” with a 20 to 80% probability of Supercooled Large Droplets (SLD). For additional weather information see the meteorology factual report in the public docket for this investigation.

Figure 4 - Icing probability and severity charts with accident location annotated.

A search of archived information indicated that the accident pilot(s) did not request weather information from Leidos Flight Service. The accident pilot(s) did use their ForeFlight account to gather and receive a weather briefing through ForeFlight about 2008 on October 17. The ForeFlight weather briefing from 2008 on October 17 contained all the standard weather forecast information valid then through the proposed departure and flight time, starting at 0630 on October 18. While the text AIRMETs (Sierra and Zulu) were highlighted for the accident flight route, the G-AIRMETs were not forecast for the region after 0500 due to it being beyond the G-AIRMET forecast issuance timeframe. No weather imagery was viewed in the ForeFlight application before the flight. AIRPORT INFORMATIONThe airplane was a high-performance, conventional-tail, pressurized, twin-engine turbo-propeller airplane and was designed and equipped for flight in instrument meteorological conditions, day or night, and into known or forecast icing conditions. The surface deice system would remove ice accumulation from the leading edges of the wings and stabilizers through the use of pneumatic boots. Ice would be removed by alternately inflating and deflating the deice boots. Pressure-regulated bleed air from the engines supplied pressure to inflate the boots. A venturi ejector, operated by bleed air, created a vacuum to deflate the boots and hold them down while not in use. To assure operation of the system in the event of failure of one engine, a check valve was incorporated in the bleed air line from each engine to prevent loss of pressure through the compressor of the inoperative engine. Inflation and deflation phases were controlled by a distributor valve. A three-position switch in the ICE PROTECTION group on the pilot's subpanel, placarded SURFACE DEICE - SINGLE - OFF MANUAL, controlled the deicing operation.

The switch was spring-loaded to return to the OFF position from SINGLE or MANUAL. When the SINGLE position was selected, the distributor valve would inflate all of the airframe boots, both wings and tail. After an inflation period of approximately 7 seconds, an electronic timer switched the distributor to deflate the boots. After these boots have inflated and deflated, the cycle was complete. When the switch was held in th...