At approximately 11:15pm on June 24, 1972, the aircraft crashed while attempting to land at Mercedita Airport.

[1] Just after touching down on the runway at Mercedita Airport the flight crew made a decision to go around.

[1] The National Transportation Safety Board (NTSB) investigation concluded that the probable cause was the "presence of an unauthorized vehicle on the runway which caused the pilot to attempt a go-around after touchdown to avoid a collision.

[1] This was based on eyewitness accounts of a set of lights visible on the runway as Flight 191 approached, and other eyewitness accounts of a vehicle owned by the Puerto Rico Ports Authority being parked shortly after the accident and the driver acting in a suspicious manner.

[1] Three years after the accident the NTSB was compelled to re-open the investigation into the crash, after submissions were received that the person who was suspected of driving the "unauthorized vehicle" had actually left the airport about fifteen minutes before the aircraft crashed.