I'm not sure what the info coming out of Prospect is... but I know PCS had held back on giving out any info on the 'negotiations' but finally reached a point where they said they felt the offer coming from NATS was so insulting that they were compelled to make it public knowledge.
My guess is if there is no significantly improved offer forthcoming then they'll be putting it to the members' vote with a recommendation to reject. We're then into ballot for industrial action territory.
My personal impression is a number of the senior guys (in PCS anyway) are fully aware that they're under pressure from some questionable judgement calls the last time round and are ready to dig in.