What happened
On March 21, 2024, a Beechcraft C-90 operating as an air ambulance was conducting a non-scheduled medical transport flight from Montería (SKMR) to Medellín (SKMD). The crew, consisting of a pilot, co-pilot, a physician, and a nurse, was flying under Instrument Flight Rules (IFR) at a planned altitude of 19,100 feet.
While cruising at 19,100 feet, the pilot reported abnormal indications regarding the left engine, accompanied by a gradual loss of altitude. The pilot subsequently requested a controlled descent to a lower altitude. During the descent, the pilot requested priority for landing at Olaya Herrera airport, noting that the aircraft was struggling to maintain performance.
Radio communications between the crew and another pilot revealed the crew's increasing distress. Despite the other pilot's advice to fly calmly toward Medellín, the pilot of HK4684 eventually declared a MAYDAY, stating that the aircraft could no longer maintain its flight path. Shortly thereafter, the aircraft lost ADS-B tracking. A commercial flight crew in the vicinity later reported seeing fire and smoke rising from the crash site near Santa Rosa de Osos. The impact with the mountainous terrain resulted in four fatalities and significant structural damage to the aircraft.
The investigation
The GRIAA investigation examined the aircraft's maintenance history, engine and propeller condition, and flight parameters. Investigators reviewed radar tracks and ADS-B data, as well as cockpit voice recorder (CVR) audio. The investigation also analyzed meteorological data and flight data from other aircraft in the area to determine if icing conditions were a factor.
Technical inspections were conducted on the engines and propellers, and the investigation is currently evaluating the reliability of the engine maintenance program, specifically regarding the implementation of a Supplemental Type Certificate (STC) intended to extend the Time Between Overhauls (TBO) under the MORE 13 program.