The helicopter is most vulnerable when taking off or landing.
Rockets were already flying chaotically, but fortunately, while RPGs are easy to launch, where they land is not determined by human will. The further they travel, the more they rely on fate. Even with extensive training, it's not possible to accurately predict the impact point of an RPG.
Those close enough would get shot down by the three helicopters. The likelihood of launching rockets at close range, as what happened to the U.S. Army helicopters in Mogadishu, is slim.
As for those at a distance, let them shoot their RPGs. There's no way to prevent it; it all comes down to luck.
But anti-aircraft missiles are a different story.
Night Demon Three was flying at just over fifty meters, and it hadn't yet picked up speed. It was at its most vulnerable.
Even a shoulder-fired anti-aircraft missile, if it hit at this moment, would make one contemplate the possibility of going to the crash site to see if anyone survived.