"Targets destroyed." Yinn and Tellie reported at the same time as they saw the surface to air missiles controlled by Nie had already flown the moment those small blasts EMP missiles reached their target. They knew that the Mecha Smith apprentice was watching consistently on the screens to ensure that their timing would match and not give any chance or window of opportunity for the enemies to gain back their momentum.
The exterior of the helicarriers exploded causing a hole to rip open and the Grey Bears could see Mechanoids dropping out from the hole as part of the aircraft descended. The problem was that there was no escape from them as the Grey Bears purposely timed their shot so that the aircraft would drop into the valley. With the aid of the System's topography, they were able to make sure that the timing was accurate so that there was no way those enemy Mechanoids would come bug them once they fell into the bottom of the valley.