The 'pull up' callout is the classic Ground Proximity Warning System alert, the automated voice that warns pilots of dangerous terrain closure and commands an immediate climb. Heard in airliner cockpits since the 1970s, when terrain warning systems became standard equipment, it is one of the most recognisable sounds in aviation. The Boeing 707, the pioneering four-engine jet airliner of the late 1950s, gives this clip its vintage flavour. Online it circulates through flight simulator videos and aviation meme edits, where the urgent command turns any close call into instant comedy or tension.