Brad Pitt 'lunged at son Maddox when he tried to defend mum Angelina Jolie on private jet'

 Following claims Angelina Jolie filed for divorce because Brad Pitt was abusive to the kids, it has now been reported Brad Pitt "lunged" at his son Maddox during a flight on a private jet as the teen tried to defend his mum Angelina Jolie.

According to TMZ, Brad began arguing with his wife mid-air, and when Maddox jumped up to defend her, he allegedly "lunged" at his son.According to the site ..

Here's what's alleged -- Shortly after the plane took off, Brad and Angelina began arguing and Maddox jumped up to verbally defend his mom. We're told Brad then lunged at the boy and Angelina jumped in between them to block her husband. Brad connected in some fashion with his son.

Now here's what's in dispute:
-- Whether Brad and Angelina were arguing, or whether Maddox was acting up on the plane.
-- Whether Brad made contact with his son intentionally or inadvertently.
-- Whether Brad was drunk at the time. Although authorities were told Brad was drunk when the incident went down, we're told Angelina says he was sober at the time but got drunk later in the flight. Sources connected with Brad tell TMZ he was drunk at the time of the incident.

 Angelina wants sole physical custody of the kids. A source connected with Angelina says this is not about alcohol ... she would never leave Brad if it was just a substance abuse problem. The source says this is all about protecting their children.