Pequod during the 1980s.
Pequod was the callsign for Diamond Dogs' helicopters during the 1980s. From what can be seen, it is the designated codename for the chopper responsible for personally assisting Venom Snake, whether it be simple transportation or dispatching assistance as part of the Support Unit, although Pequod pilots have also assisted other Combat Unit members as well.
One Pequod pilot was killed by the Parasite Unit's metallic archaea while transporting Venom Snake and Code Talker out of the Angola-Zaire border region. The chopper's windshield was shattered, causing glass to fly into his face.
Behind the scenes
Pequod follows the trend of Moby-Dick-based codenames in Metal Gear Solid V: The Phantom Pain. In the novel, the Pequod was the title of the ship commandeered by Captain Ahab in his quest for revenge on the white whale - at the Dhekelia Memorial Hospital, Venom Snake was labeled "Ahab", paralleling his own fight for vengeance. Other examples of Moby-Dick in The Phantom Pain include Big Boss being known as "Ishmael" while at the same hospital, and a chopper present at Diamond Dogs' attack on OKB Zero being designated "Queequeg."