Which of the following is NOT detected by the CMWS with HFI-enabled ECU?

The choice indicating that grenades are not detected by the CMWS (Common Missile Warning System) with HFI (Hostile Fire Indication) enabled ECU (Electronic Control Unit) is correct because the CMWS is primarily designed to detect aerial threats, particularly those that come from missiles or aircraft.

CMWS operates using infrared sensors and other advanced technologies that respond to the heat signatures and the flight patterns of incoming missiles and aircraft. Grenades, on the other hand, are generally considered short-range threats and do not have the heat signature or trajectory that the CMWS is calibrated to detect. Furthermore, CMWS and similar systems are set up to handle threats at a different scale, thereby making them ineffective at identifying or responding to the immediate and low-altitude threat posed by grenades.

In contrast, the detection capabilities of CMWS are well-suited for identifying missiles and aircraft, which have specific flight profiles and heat signatures that can be distinguished by the system, enabling timely warning and countermeasures. Laser threats are also addressed due to their potential to pose risk to aircraft, prompting the need for awareness and countermeasures against such directed energy threats.