The Boeing 747-400 typically achieves a takeoff speed of around 250 kph, which can vary based on factors such as weight and weather conditions. Heavier loads require higher takeoff speeds due to the need for increased lift. The actual rotation speed is determined by the aircraft's operations manual, which accounts for air density and loading. Pilots focus on dynamic air pressure rather than ground speed when determining the appropriate moment to rotate. Understanding these factors is crucial for grasping the complexities of takeoff performance in the 747-400.