She sank suddenly on high seas some 130-150 km off the coast west of Nouadhibou, Mauritania on 11 March 1980 after several internal explosions, presumably related to malfunctions in the inert gas system.
During the return trip from Algeciras to Ras Tanura (on which her fatal accident happened) the ship was unloaded, on ballast.
On 4 March 1980 the María Alejandra arrived to Algeciras Bay and unloaded the oil she brought from the Persian Gulf in the CEPSA refinery.
In the first hours of 8 March she left port again, however the problems with the inert gas system were not fully resolved yet, and the crew were working on them en route.
After a stop at Las Palmas in the Canary Islands she was sailing south along the western African coast headed for the Cape of Good Hope and the Indian Ocean.