What happened
On September 21, 2023, an Embraer EMB-545 MOD aircraft, registration N434FX, was performing a GPS approach to Runway 4 at St. Simons Island Airport (SSI) in Georgia. The flight, operated by Flexjet LLC, departed from Westchester County Airport (HPN) in New York. The weather at the time of the accident involved gusting winds and visual meteorological conditions.
As the aircraft descended through approximately 150 feet above ground level, the pilot reported feeling an "uplift" while crossing a tree line, after which the airplane began to porpoise. The pilot attempted to correct the pitch using the sidest andick, but the aircraft did not respond as commanded. The copilot observed the pilot making aggressive inputs and noted that the airplane's response was unresponsive.
During the flare, the aircraft experienced a horizontal gust that reduced the indicated airspeed by approximately 8 knots. The airplane touched down hard on the runway before the threshold, bounced, and then slid along the runway for over 3,000 feet. The aircraft eventually exited the right side of the runway, struck a sign base, and came to rest in the grass. There were no injuries to the two crewmembers or the six passengers.
The investigation
An investigation of the flight data recorder (FDR) and cockpit voice recorder (CVR) revealed that the airplane's angle of attack (AOA) limiter protection system engaged at a radio altitude of 162 feet. This engagement was triggered by a sudden increase in AOA, likely caused by a wind gust.
While the AOA limiter protection performed according to its design, it restricted the flight crew's ability to use the remaining stall margin to pitch the nose up during the landing flare. Specifically, the FDR showed that even when the pilot commanded full nose-up pitch, the fly-by-wire system provided very limited elevator deflection. The investigation found that the pilot's rapid, oscillating pitch commands prevented the system from meeting the specific criteria required for the AOA limiter to disengage.
Findings
- The AOA limiter protection system engaged due to a sudden increase in AOA caused by a wind gust.
- The flight control computer software prevented the AOA limiter from disengaging because the pilot's frequent and large pitch inputs failed to meet the required load factor stability threshold.
- The activation of the AOA limiter protection limited the flight crew's ability to control the airplane's pitch during the landing flare, resulting in a hard landing.