What happened
On August 30, 2002, at approximately 18:00 local time, an Embraer 120, registration PT-WRQ, was performing a scheduled flight from Cruzeiro do Sul to Presidente Médici, with a stop in Tarauacá. The aircraft was carrying three crew members and 20 passengers.
During the night approach to Rio Branco, the aircraft was operating under instrument flight rules (IFR) due to deteriorating weather conditions, including thunderstorms and low ceilings. While on final approach to runway 06, the aircraft struck the ground approximately 2.14 NM from the threshold. The impact caused severe damage to the aircraft, which was later determined to be a total loss. The collision also resulted in the deaths of six cattle on a nearby farm.
The investigation
CENIPA investigators examined the aircraft's engines, propellers, and flight instruments. Analysis of the Pratt & Whitney engines revealed that both were operational and producing significant power at the moment of impact. However, the investigation identified several maintenance discrepancies in the aircraft's recent history, including deferred corrective actions for a malfunctioning radio altimeter and a windshield wiper issue. Additionally, the aircraft's Ground Proximity Warning System (GPWS) was reported as inoperative at the time of the accident.
Investigators also noted a discrepancy in the altimeter settings between the pilot and co-pilot, which resulted in an altitude difference of approximately 70 feet. The investigation focused on the flight crew's adherence to the Minimum Descent Altitude (MDA) of 1150 feet, as the aircraft descended below this limit before impact.
Findings
- Controlled Flight Into Terrain (CFIT): The aircraft descended below the established MDA of 1150 feet during the final approach.
- Psychological Factors: The crew experienced high levels of anxiety and pressure to complete the landing due to the high passenger load and deteriorating weather, which contributed to a loss of situational awareness.
- Operational Deficiencies: There was a lack of effective Crew Resource Management (CRM) and coordination within the cockpit, leading to a failure to monitor the descent profile.
- Adverse Weather: Heavy thunderstorms, low visibility, and low ceilings necessitated IFR procedures and complicated the approach.
- Environmental Factors: The rural, poorly lit surroundings of the airport made visual references difficult during the night approach.
- Procedural Deviations: The aircraft was configured with the landing gear up and flaps at 15 degrees, deviating from the company's standard operating procedure which required gear down and flaps at 25 degrees for final approach.