Parsa and Kapadia (1997) used the BDI to survey a group of 57 U.S. Air Force fighter pilots who had flown combat operations. The adaptation of the BDI to the aviation field was problematic. However, the study revealed some unexpected findings. The results indicated that 89% of the pilots reported insomnia; 86% reported irritability; 63%, dissatisfaction; 38%, guilt; and 35%, loss of libido. 50% of two squadrons and 33% of another squadron scored above 9 on the BDI, suggesting at least low levels of depression. Such measurement may be difficult to interpret accurately.