[tombert]

Or the parent should just take the phone away! If the kid won't listen to it quietly then they should do that thing that I believe is called "parenting". Bring a picture book or something for them if they need to be entertained without the phone.

This was done by my parents when I was a young kid. I wouldn't turn the volume down on my Game Boy on a flight, so my parents took it away from me until I promised to keep the volume down, which I did after that.

[CamJN]

I've been on a flight where a set of parents took away their child's tablet, not for being noisy but as punishment for some other bad behaviour. What resulted was 6 hours of a child screaming on an 8 hour flight. Aside from wanting to punt the little shit out the door, I was almost impressed at the kid not giving up after a few minutes, and then hours when nothing changed.

[tombert]

I still think that's less actively inconsiderate than Cocomelon at full volume. At some level they can't control the kid crying but they can control the volume which their kid's media runs at.