No, you're NOT at an impasse. If you were at an impasse, the mediator would issue a proffer of arbitration. You got parked because one or both sides weren't "behaving" in a manner to move the process and the mediator is sending a message to shape up.

In fact, the agreement for the flying may well work in your favor and give you additional leverage if your people don't get foolish and think they can get the moon. The mediator will likely be looking at this move and the company financials and abilities differently now.

Bring your A game and leave the egos and arrogance at the door. (That's not directed specifically at you or your group, but SOP in a situation like this)

Good luck.