What initiates the movement of the ejection seat during the ejection process?

The ejection seat's movement during the ejection process is primarily initiated by detonated gas pressure. This pressure is generated by a pyrotechnic system that is triggered when the pilot pulls the ejection handle. The explosive charge ignites, producing gas that rapidly expands and forces the seat out of the aircraft. This method is designed to ensure a quick and reliable ejection, allowing the pilot to escape safely in emergency situations.

Other potential options do not play a primary role in initiating this movement. For instance, while manual pilot action is required to pull the ejection handle, it is the resulting gas pressure that actually drives the seat out of the aircraft. Electrical activation may be involved in various systems but does not directly cause the initial ejection. Gravity loading is not a factor in the ejection process since the system is designed to act independently of gravity to safely propel the seat upward and away from the aircraft.