initially developed by evergreen international aviation, the first supertanker was based on a 747-200 (n470ev, tanker/tail number 947), and never entered service. the second supertanker (n479ev, tanker/tail number 979) was based on a 747-100 originally manufactured by boeing in 1971 for delta air lines. it entered service for the first time in 2009, fighting a fire in cuenca, spain, and made its first american operation on august 31, 2009 at the oak glen fire in california. it is no longer in service.