Actually it's only the Flexiscrew guys who have been in the company for 18 months or more who will get the permanent contracts. IF the new pay deal is accepted by the workforce.
Perm contracts have been offered to flexicrew with as little as 200 hours in order to fill certain base crewing requirements. The usual is 6 months, or 500 hours.
The pay deal clause is in addition I believe, meaning if you last 18 months without applying for one of the perm contracts you will be offered one without having to go through all the hoopla.