The UPS Pilots' union (I.P.A.) put out a nice timeline that details the RLA steps here: Independent Pilots Association

The one thing that they don't mention, and many have alluded to here, is what actually can happen after a PEB if Congress does get involved. They CAN impose contract terms on both parties. In order to do so Congress has to believe that a strike / lock-out would irreparably harm the economy of the U.S.

Likely that it would ever get that far? No.

Possible? Yes, but so is winning the lottery.

Good luck!