It is one of those airline conundrums that Fleet Planning will work out a particularly lean and efficient game plan with no slack, knowing that if they get into an AOG difficulty they can always subcharter in from the Spanish/Lithuanians, probably at less overall cost than having their own spare. Meanwhile the Finance team, working in a parallel universe, and maybe driven by commands from Germany (other owners are available) look at the simplistic cost per hour of subcharters and say "no more hiring in - do it with your own resources".