You realize that you aren't asking to "be realeased" or "to walk" right? You guys are asking for a proffer of arbitration, you're basically asking the NMB to offer to arbitrate any remaining issues. The NMB may not issue a proffer of arbitration and keep both sides in mediation.

If they do offer arbitration either side can deny it. If this happens you go to a 30 day cooling off period and then you and the company are released to self help [strike for you & the company can deviate from the status quo (basically do whatever it wants to you within FAA regs.)]

If the union and company both accept the "proffer of arbitration" then whatever the arbitrator decides is LEGALY BINDING for the length of the contract.

So the questions are:

Will the NMB mediator(s) issue a proffer of arbitration? Or will they try to continue with mediated negotiations? The company does not want to be offered arbitration because they know the union may turn it down - then the ball is in your court.

Will the company accept arbitration if it's offered?

Will the union accept arbitration if it's offered? Or are they just asking for this so they can decline it and get the ball rolling on a strike? (I assume this is what's going on)

The NMB sets no time table to consider requests like this so I'm not even sure how long it will take for the mediator issue a proffer or decide not to.

Hopefully that clarified some stuff. Good luck!