What happened
On August 19, 2018, a Stemme S12 motor glider, registration N612ST, was performing a recreational VFR flight near the Rancho Arriba and Bonao areas, approximately 30 nautical miles northwest of Aeropuerto Internacional Dr. Joaquín Balaguer (MDJB). After two hours of flight, the pilot initiated a return to the airport.
While established in the traffic pattern, the pilot requested to cross the station vertically to the east. However, air traffic control instructed the aircraft to maintain its position northwest to avoid incoming IFR traffic. During this period, the pilot reported radio difficulties. As the aircraft progressed on its final approach to runway 19, air traffic controllers observed black smoke emanating from the aircraft.
In an attempt to ventilate the cockpit due to smoke and fire, the pilot ejected the aircraft's canopy, which was later recovered approximately 700 meters north of the impact site. During the final descent, the left wing struck a tree, causing the aircraft to pitch nose-down and impact the terrain approximately 0.5 nautical miles north of the airport. The impact and subsequent fire, fueled by ruptured fuel tanks, destroyed more than 95% of the aircraft. The two fatalities on board were the pilot and one passenger.
The investigation
The CIAA investigation examined the aircraft's maintenance records, flight communications, and the wreckage. Investigators analyzed the cockpit communications, which confirmed that radio contact remained functional and fluid until the pilot reported the malfunction. The investigation also reviewed the condition of the ejected canopy, which showed evidence of soot and exposure to fire.
Physical evidence at the scene indicated that the aircraft's descent was interrupted by contact with vegetation, specifically trees reaching heights of 25 to 40 feet, which contributed to the loss of control. The investigation also noted that the dense vegetation in the area delayed search and rescue efforts by approximately one hour and 40 minutes.
Findings
- The primary contributing factor was an in-flight fire originating from an unidentified station within the cockpit.
- The pilot successfully ejected the canopy to mitigate smoke inhalation, but the fire was already established within the cabin.
- The impact with a tree during the final moments of flight caused a sudden left turn and a nose-down attitude.
- The destruction of the fuel tanks upon impact led to a massive post-crash fire that consumed nearly the entire airframe.