As title, I operate only 1 fleet group, the ATR42/72.
When I have 4 of them, my staff salaries = 324961 and staff training = 17790 - 21311
When I add another ATR72, staff salaries = 460965 and staff training = 35111
Previous aircraft flying 5 routes a day and this one fly only 4 routes. Yet the cost increment is very big and seems out of balance.