What happened
On September 19, 2014, an Embraert ERJ 135 was operating at flight level 410 (FL410) when the aircraft experienced a sudden increase in indicated airspeed (IAS). This acceleration resulted in an overspeed condition, which triggered the aircraft's Master Warning HIGH SPEED alert. The airspeed exceeded the maximum allowable limit by approximately 5 knots for a duration of about 11 seconds.
The investigation
The PKBWL investigation focused on the flight data recorded by the Flight Data Recorder (FDR). Following the incident, the aircraft manufacturer was notified and permitted the aircraft to continue operating for 10 flight cycles pending the analysis of the FDR data. Upon completion of the data review, no structural or mechanical issues were identified that necessitated additional inspections of the aircraft.
Findings
- The primary cause of the overspeed was the crew maintaining a narrow margin between the operating airspeed and the maximum allowable speed, particularly given the prevailing and forecast turbulence conditions.