The 747 was an Earth airplane in operation during the late 20th century.
The airline British Airways (BA) operated this airplane type. On a large billboard in San Francisco, BA advertised its services with a picture of 747 in flight.
In 1986, the humpback whales George and Gracie were transported from the Cetacean Institute in Sausalito, California to the Bering Sea off Alaska via a 747. The aircraft was specially modified to carry the two humpback whales that distance. (Star Trek IV: The Voyage Home)
It is likely this was a reference to the Boeing 747, one of the largest commercial jetliners in the world.