UA it appears is taking back some of what they gave to the employees in the recent negotiation. The unions didn't include any bonus in their contract, and UA is now changing that elective aspect of compensation. Pretty typical and not collectively bargained, so if it was that important did they didn't collectively bargain this into the negotiations? My guess is they knew UA would perhaps change this and is why they were heavy on $ compensation. If I was one of the bargaining team, I would lay out what is and isn't collectively bargained in terms of compensation and assume any elective compensation on behalf of the employer may be at risk.