As ML Centre is, to use Airservices own figures, around 20 ATC's short of minimum staffing requirements, and because management are on a strict "productivity" contract, this will become even more common (in southern district anyway). Managers who blow out their overtime budgets don't get paid a bonus, and even when they do call out an emergency replacement/overtime shift for a controller who has called in sick for example, the chances are the person they are callling has already worked 8 or 9 shifts in a row and will tell them to shove it. Its a catch 22, no staff, lots of overtime, increasing absenteeism, more overtime. The ultimate result is TIBA/restricted airspace