Carl XVI Gustaf (Carl Gustaf Folke Hubertus; born 30 April 1946) is King of Sweden. He ascended the throne on the death of his grandfather, Gustaf VI Adolf, on 15 September 1973. He is the youngest child and only son of Prince Gustaf Adolf, Duke of Västerbotten, and Princess Sibylla of Saxe-Coburg and Gotha. His father died on 26 January 1947 in an airplane crash in Denmark when Carl Gustaf was nine months old. Upon his father's death, he became second in line to the throne, after his grandfather, the then Crown Prince Gustaf Adolf. Following the death of his great-grandfather, King Gustaf V, in 1950, Gustaf Adolf ascended the throne and thus Carl Gustaf became Sweden's new crown prince and heir apparent to the throne at the age of four.