IMO. FWIW, both parties are irresponsible. But as Mom is not posting here I am just addressing the OP, who knowingly got on her flight (put the phone on AP mode) despite knowing that there was no one to pick up and watch the 10 year old child. She, at that time, was still responsible for this child.
I do hope that the parent was able to get someone to pick up and sit for her daughter till she got home. OP has been back here several times and still not answered the question that was asked a couple of times..."Is the child okay?" One can only assume that she has no idea if the child is safe...her only concern seems to be CHA.