On July 30, 1999, during the celebrations of the 20th Anniversary of the Sandinista Air Force (FAS), a squadron of six Mil Mi-17 helicopters led by Major Onofre Guevara was scheduled to perform a low-pass in close formation over the runway at Managua’s Augusto César Sandino International Airport.
The maneuver, intended to greet the attendees and high-ranking military officials, required the helicopters, flying in three pairs, to descend, perform the low-pass, and then climb to leave the area. However, something went terribly wrong.
During the ascent maneuver after the low-pass over the runway, the helicopters in the first formation came too close to each other, and their rotor blades collided. The Mi-17 with the serial FAS-321 (MSN 419M35), piloted by Lieutenant Carlos Marvin Osorio Lupone, veered sharply to the right after its main rotor lost balance and the blades broke, causing it to spin uncontrollably on its axis. Seconds later, the tail boom detached from the aircraft, sealing its fate. The helicopter exploded and hit the ground engulfed in flames.
The leading helicopter in the formation, the Mi-17 with the serial FAS-318 (MSN 419M32), piloted by Major Guevara, immediately entered autorotation and managed to make an emergency landing on the airport runway. The remaining helicopters in the squadron, which had broken formation seconds after the collision, moved away to maintain a holding pattern until they were authorized to land.
In addition to Lt. Osorio Lupone, the accident claimed the lives of Lt. Justo Pastor Cabrera Orozco, who was the co-pilot, and Eddy Alberto Altamirano Vásquez, the flight mechanic.
The cause of the accident was attributed to “human error,” which was reinforced by testimonies from former FAS officers who stated that during the practice session held the day before the accident, the pilots in the squadron had informed the Flight Director that Osorio Lupone had flown too close to the lead helicopter during the maneuvers.
Ironically, just the year before, Osorio Lupone, the youngest of the FAS aviators, had been recognized for his courage in the rescue operations during the emergency caused by Hurricane Mitch.
Here is a video of this tragic accident: