What initiates the CFS during the ejection sequence?

The correct response focuses on the role of the underseat manifold canister in the ejection sequence. During an ejection, the CFS (Canopy Fracturing System) is activated to ensure that the canopy of the aircraft is shattered, allowing the ejection seat to exit safely from the cockpit. The underseat manifold canister contains a pressurized gas that is released to initiate this process. When the ejection sequence is initiated, the canister rapidly expels gas, which operates the CFS to fracture the canopy.

While the PIRD mechanism does contribute to the overall ejection process by controlling the pyrotechnics involved, it does not directly initiate the CFS. Similarly, the pilot's command is crucial for activating the ejection sequence, but the mechanical action required to shatter the canopy comes specifically from the underseat manifold canister. The ejection seat's rocket motor plays a role in propelling the seat away from the aircraft once the canopy has been cleared but does not initiate the canopy fracturing itself. Therefore, the activation of the CFS is correctly attributed to the function of the underseat manifold canister in this context.