I am not sure when you bought them. But perhaps it is just the 'old surprise' that you pay the first 4 leases upfront and they are not cash effective during the first 4 months of operating this particular plane. After the first 4 months, the leases of that particular plane become cost effective in your income statement as a weekly expense. If you keep ordering new planes, at the beginning you make a profit easily, since the leases are not counted in yet. As those planes pass their first 4 months of operations, they start to cost the effective amount. When calculating direct profit on the airplane summary page, those leasing costs are stated, but not yet cost effective. The positive earnings presented there are Earnings after Direct Costs (EADC). The general costs still get deducted in the income statement. Perhaps, you continued to order planes and now those leasing rates kick in?
Denis