TMZ has learned … Rick Ross' private jet made an emergency landing in Birmingham, Alabama, 2 hours ago, en route to his concert in Memphis … and we found out he suffered another seizure.

It's the second time today where a plane in which the rapper was a passenger made an emergency landing.

We broke the story … Rick suffered a seizure this morning on a Delta flight that returned to the Ft. Lauderdale airport. Rick went to the hospital, was released, and then took off at 5:07 PM ET from Ft. Lauderdale to make his concert tonight in Memphis.

But at 5:44 PM CDT, the plane was diverted and landed in Birmingham after Rick had a seizure on board. Rick is currently in a Birmingham hospital emergency room. We do not know his condition. Before Rick took off from Ft. Lauderdale, he tweeted a video showing he was ok.

Ross was supposed to be on stage in Memphis at 7:30 PM ET.