Comments from parents flooded in, with most being disgusted, including Ms Kathleen.
She said: "All she needed to do was walk a few feet to the back of the plane and into the lavatory."
Kim Lovell said: "She's nasty and gross for doing that."
Gina Zanghi, meanwhile, said: "That child is pretty small, couldn't she have put a diaper on them, rather than carry a potty on-board?"
And Kannika M Mungkung said: "This act is very disgusting in any public place, not to mention a closed environment like an airplane."
But some took a different position.
Margaret McManus said: "Have you seen how tiny the toilet cubicle is on a plane?! Not a chance of fitting a toddler and a potty and a mum in there! Toddler wee is like a dribble of water, hardly going to send a cascading torrent down the aisle! Get over yourselves, you'd soon be complaining if the little one wet themselves while waiting for the cubicle!"
Another supporter wrote: "Are you all out of your minds? This is a little kid they probably needed to pee... that pee is probably the cleanest thing on that airplane. You go mom!"
And Manda Coen commented: "You guys all need to lighten up, seriously. This is hilarious! If I saw this in person I would just die laughing!"
Parenting expert Sue Atkins is sympathetic towards the passenger.
She told the MailOnline: "I don't like naming, shaming or blaming parents - it's a tough job and parents need a helping hand not a pointy finger. We're all doing our best so instead of shaming how about helping?"