In recent years, most Cost Adjustment Sheets (CASs) have increased the Navy's Flying Hour Program (FHP) budget. They also have been far more utilized by the F/A-18 program than by program offices for most other types of naval aircraft. RAND assessed the contribution of CASs to the accuracy of FHP budgets and whether CAS usage is correlated with expenditure-per-flying-hour growth, as well as why CASs have been used more by the F/A-18 program.