Measuring safety by comparison is difficult. The Royal Australian Air Force's (RAAF's) MacKinnon explains: "The problem with measuring performance with other nations is that there are a number of definitions as to what constitutes an accident." For example, what the Royal Air Force calls a Category 4 accident is close to, but not identical to the US Air Force's Class A Mishap.
Air force size influences how performance can usefully be measured. The RAAF is a small air force, so using annual figures makes graphs very spikey even though the number of accidents may vary hardly at all: for example, a single accident may double an annual rate. MacKinnon explains: "We use a five-year 'rolling' average to assess any trends, because individual years are too erratic when using a smaller sample." Using the rolling-average, he says, shows that the RAAF "compares favourably with the RAF, Canadian and USAF".
Tools for safety-performance measurement within the RAAF are being developed. MacKinnon says: "We're just introducing a safety programme to all the bases in Australia, which will help us identify how well we're performing, and will give a direction for people who are setting up a flight-safety programme."
With the programme only in draft form so far, however, MacKinnon cannot detail it. He adds: "Any programme suggested by us can only be a skeleton, because [it] will be dictated by the type of aircraft flown and its operation, such as fighter and transport. We believe we're moving in the right direction. The main philosophy is to preserve the air force's human and material assets."
In fiscal year 1982, the USAF achieved only a 2.5 accidents/100,000 flight hours Class A mishap rate for fighters, bombers, trainers and support aircraft. The rate was down to 1.5 in FY1994, which was the average for the 12-year period. Achieving and sustaining a 1.0 rate is a reasonable goal, says Godsey. In FY1991, 1.1 had been achieved, but the rate shot up to 1.6 in the following year before dropping to 1.3 in FY1993.
The excellent rate in 1991 was achieved, despite US military involvement in the Gulf War, but Godsey cautions that the safety picture, was artificially improved by the dramatic build-up in cargo/tanker aircraft transit flight hours, in support of the Middle East conflict. He also notes that the time flown by USAF aircraft in combat is never counted in grading flight safety.
Safety worsened, however, with the cessation of the fighting. Godsey explains that fighter pilots trained primarily for air-to-air missions were used in the conflict to protect other US air assets and to attack ground targets. Upon returning to home bases, the aviators found they had lost their edge in performing their primary missions, and as a result the accident rate reached a peak. An intensive retraining programme was instituted and safety improved.
Between FY1989 and FY1994, 56% of all major air accidents were caused by operational mishaps, including mid-air collisions, ground impacts, wing stalls, control loss, gear-up landings, fuel starvation and bird strikes. Nearly 40% of all the accidents in the same period, were caused by aircraft issues, such as engine problems and fuel imbalance. That ratio remains true for FY1994 Class A mishaps.
Godsey also points out that data analysis shows that 16 of the 36 Class A mishaps during FY1994 were caused either to violation of a directive or what the USAF officially calls "dumb decisions". Between FY1989 and FY1994 about 70% of all aircraft losses were caused by loss of control.
Source: Flight International
