What happened
The crew initiated the descent checklist, which had been approved by the manufacturer. During the descent phase, the aircraft encountered weather conditions consisting of clouds with a thickness of approximately 2,500 feet. The outside air temperature (OAT) was recorded as being below freezing during this period.
Despite these environmental conditions, the auto-ignition switches were not engaged in the continuous or automatic position. As the aircraft approached its destination, both engines ceased operation simultaneously while on final approach to land.
The investigation
Following the incident, the operating company conducted an internal review of the event. Mechanical examinations and operational data analysis were performed to determine the root cause of the engine failures. Investigators focused on the relationship between the weather conditions, ignition settings, and engine performance.
Findings
The company concluded that the flameouts were caused by ice ingestion into the engines. The lack of continuous ignition in freezing conditions allowed ice accumulation that disrupted combustion. Despite the dual engine failure, the airplane was successfully landed without sustaining any damage to the airframe or systems.
Safety message
This incident highlights the critical importance of utilizing auto-ignition systems during descent through known icing conditions. Continuous ignition is necessary to prevent flameouts caused by ice ingestion when temperatures are below freezing.