Brandon T. Jackson -- I Wasn't A Drunken A-Hole On Plane

Brandon T. Jackson says 13 people on his US Airways flight will back up his story that a flight attendant hurled the "N" word at him and made another racial comment.

Brandon's rep tells TMZ ... the incident Monday did not go down the way the airline claims. The rep says he was NOT drunk, NOT loud, and NOT disruptive.

Here's the way Brandon says it went ... He was running lines for a script he had with some random passenger who was sitting next to him. The flight attendant then accused them of being too loud, but Brandon says the noisy ones were actually in the row in front of them.

So the "Tropic Thunder" star claims he then went to the back of the plane for sandwiches, and the flight attendant confronted him, told him she didn't care if he was Obama's son and he needed to sit down. He also says she hurled an epithet, "seemingly in jest." He claimed earlier she used the "N" word.

Brandon says the flight attendant beat him to the punch and complained to the pilot and when they landed he was questioned by authorities, who determined he was NOT intoxicated as the airline claimed.

Brandon says he has 13 passengers who waited around to back up his story.