Why did Magellan not complete the sail around the world?

Ferdinand Magellan was a Portuguese explorer. He is best known for having planned and led the 1519 Spanish expedition to the East Indies across the Pacific Ocean to open a maritime trade route, during which he discovered the interoceanic passage bearing thereafter his name and achieved the first European navigation from the Atlantic to Asia. During this voyage, Magellan was killed in the Battle of Mactan in 1521 in the present-day Philippines. After that, Juan Sebastián Elcano took the lead of the expedition, and with its few other surviving members, in one of the two remaining ships, completed the first circumnavigation of the Earth when they returned to Spain in 1522. Granted speci