What happened
On September 21, 2023, an Embraer SA EMB-545 MOD, registration N434FX, operated by Flexjet LLC, was involved in an accident during its approach to St. Simons Island Airport. The flight, operating as Flexjet flight 434, had departed from Westchester County Airport in New York. The flight crew, consisting of a pilot and copilot, along with six passengers, were all unharmed during the event.
During the final approach, the pilot utilized a GPS-based runway 4 approach with a flaps 3 configuration to manage gusting winds. While the approach was initially stable, the flight crew disconnected the autopilot approximately 500 feet above the ground. As the aircraft descended through 100 to 150 feet, it encountered an uplift near a tree line, causing the aircraft to begin porpoising. The pilot attempted to correct the pitch using the sidestick, but the aircraft failed to respond to these inputs. The copilot noted that the pilot was making aggressive control movements, yet the aircraft continued to pitch up and down unexpectedly.
As the aircraft neared the runway, the flight crew received a terrain awareness and warning system alert regarding the sink rate. The aircraft eventually made a hard touchdown before the runway threshold, bouncing once before settling on the centerline. The aircraft then skidded toward the right side of the runway, striking a concrete sign base before coming to a rest in the grass. There were zero fatalities and zero injuries among the occupants.
Findings
An investigation into the aircraft's performance revealed that a sudden increase in the angle of attack (AOA), likely triggered by a wind gust, caused the AOA limiter protection system to engage. This aerodynamic stall prevention system remained active until touchdown, which limited the aircraft's response to the pilot's pitch commands. This restriction prevented the flight crew from effectively correcting the porpoising motion. Additionally, the aircraft experienced a horizontal gust during the flare that reduced the indicated airspeed by approximately 8 knots.