X17 photogs just witnessed members of Chris Brown's entourage board a private Gulfstream IV at Van Nuys airport, possibly bound for Vegas.

The jet took off at approximately 3:50 PST.

We can't confirm that Chris is on board (or if Rihanna is with him!), but with such a big expensive plane, we're sure it's not just for his bodyguards and assistants to travel in style!

Stay tuned for further updates!