@
Lorraine
I was under the assumption that the helicopter guy was infected and maybe as a last ditch effort to do something good, he wanted to save the school girls he thought survived. He circled above the school, saw all the zombies, and basically lost hope that anyone survived, and finally crushed the picture in sadness or anger, broke the medicine thinking it was all pointless, and then he lost control and crashed from turning.
Though none of this is explicitly stated, that's just how I read it at least.