What happened
On October 21, 1998, an Embraer EMB 120RT, registration PT-WKH, operated by BSB Capital Táxi Aéreo, was performing a cargo flight from Teresina to Fortaleza. The aircraft was transporting medications and carrying two crew members and one passenger.
During the approach to runway 13 at Fortaleza, the crew attempted a visual approach with a right-hand base leg. The aircraft was flying at high speeds, exceeding the manufacturer's recommended limits for the terminal area. While descending, the pilot requested the landing gear be extended. At a speed of approximately 206 knots—exceed and exceeding the 200-knot limit for gear extension—the aircraft experienced a sudden engine malfunction.
The power levers were moved below the flight idle position, which triggered the propeller control unit to move into the beta range. While the left engine was recovered, the right engine experienced an uncontrolled overspeed, reaching 123% NP. This imbalance caused the aircraft to lose control, entering a steep descent and a right-hand turn. The aircraft struck the roof of a factory and subsequently crashed into the ground, impacting a person on the ground. The impact and subsequent fire resulted in the deaths of the two crew members and the person on the ground; the passenger succumbed to injuries 48 hours later.
The investigation
CENIPA investigators examined the wreckage, including the flight data recorder (FDR) and cockpit voice recorder (CVR), as well as the engines and propeller control units. The investigation established that the aircraft was flying significantly above the stabilized approach speed. The CVR revealed that the pilot was attempting to expedite the approach due to heavy local traffic, leading to an unstable approach.
Technical analysis showed that the power levers were moved below flight idle, which, combined with the high airspeed, led to the propeller overspeed. The investigation also noted a lack of effective cockpit resource management (CRM), as the pilot flying was also handling communications, and the pilot not flying failed to intervene during the unstable approach.
Findings
- Unstable approach: The crew initiated an approach at high speeds and high descent rates, exceeding the manufacturer's recommended envelope.
- Engine overspeed: The movement of the power levers below flight idle caused the right engine's propeller to enter an uncontrolled overspeed state.
- Improper speed for configuration: The landing gear and flaps were operated at speeds exceeding the structural limits specified in the flight manual.
- Poor cockpit coordination: There was a failure in crew coordination, with the pilot not flying failing to challenge the pilot flying's unsafe maneuvers.
- Human factors: The pilot's decision-making was influenced by a desire to avoid delays caused by heavy traffic and an overconfidence in his ability to manage the high-speed approach.
Safety action
Following the investigation, CENIPA issued several safety recommendations, including:
- Mandatory verification of secondary stops in EMB 120 aircraft to ensure power levers cannot inadvertently enter the beta range.
- Implementation of CRM training for all crew members to improve cockpit coordination.
- Enhanced supervision of maintenance procedures regarding airworthiness directives.
- Educational programs for pilots regarding the dangers of unstable approaches and the risks of using reverse thrust/beta range in flight.