What happened
On October 5, 2022, a Beech A36, registration N902AT, was on an instrument flight rules (IFR) flight from Presque Isle, Maine, to Biddeford Municipal Airport (B19). The flight was being conducted as a business trip.
As the aircraft approached Biddeford, it encountered instrument meteorological conditions (IMC) characterized by light rain, drizzle, and low clouds. An AIRMET for low-level turbulence and IMC was active in the area. Air traffic control provided the pilot with vectors to the final approach course for the RNAV (GPS) Runway 6 approach. During the approach, the pilot's responses to controller instructions were delayed and incomplete.
ADS-B data showed that the aircraft's ground track was inconsistent with the approach course. The airplane passed the initial approach fix approximately 200 feet below the minimum descent altitude. As the flight continued, the aircraft passed the final approach fix at 550 feet, which was 750 feet below the required minimum altitude, with a ground speed of 58 knots. The aircraft continued to descend and eventually struck trees approximately 40 feet above the ground near Arundel, Maine. The impact was followed by a post-crash fire that consumed the cockpit and cabin.
There were 2 fatal injuries involving the pilot and the passenger.
The investigation
Investigators examined the wreckage and performed an engine test run. The engine, a Continental IO-550-B, was found to have operated smoothly during the test, accelerating from idle to maximum RPM. While the engine-driven fuel pump showed thermal damage and the aneroid bellows were punctured by impact, the engine produced power at the time of impact, as evidenced by clean cuts on severed tree trunks.
Regarding the aircraft's avionics, the plane had been equipped with dual Garmin GI 275 electronic flight instruments approximately eight months prior to the accident. These instruments were integrated with the S-TEC 55X autopilot. The pilot had approximately 33.8 hours of experience with this specific avionics suite, including 7.2 hours in actual IMC.
Findings
- The pilot's ground track was inconsistent with the RNAV approach, flying parallel to and east of the final approach course.
- The aircraft maintained an unstabilized approach with significant deviations in both altitude and airspeed.
- The pilot descended significantly below the minimum published altitudes for the approach segments.
- The weather conditions, including IMC and potential turbulence, likely contributed to a loss of situational awareness.
- The pilot's recent experience with the newly installed electronic flight instruments and autopilot interface could not be definitively determined as a factor, but the workload of the approach phase was a contributing element.