U.K. CAA Study Highlights Approach and Landing Phase Risks

Nearly half of all fatal accidents involving large (more than 5,700 kg [12,500 lb]) jet and turboprop airplanes engaged in passenger, cargo and ferry/positioning flights occurred during the approach, landing and go-around phases of flight, according to an in-depth study of worldwide accidents by the U.K. Civil Aviation Authority (CAA). The results of the study, which examined fatal accidents that occurred during the decade from 2002 through 2011, were published in a report, “Global Fatal Accident Review 2002 to 2011,” released in June. The report is available at the CAA website.¹

“Analysing air accident data is a very important way for us to understand the nature of the risks faced by the aviation industry,” Gretchen Haskins, group safety director at the CAA, said when the 134-page report was released. “It helps us identify the specific safety issues and also track trends over the long term. This allows us to focus attention where it [is] most needed and assists U.K. airlines to maintain our outstanding safety record.”

According to the report, there were 250 worldwide fatal accidents that resulted in 7,148 fatalities to passengers and crewmembers aboard the aircraft. Another 252 casualties were incurred on the ground, but CAA said that figure should be treated with caution “due to uncertainty in the number of fatalities reported for some fatal accidents.”

Of those 250 accidents, 47 percent (118 accidents) occurred during the approach, landing and go-around phases of flight — with the vast majority happening during the approach phase — and accounted for 46 percent of all on-board fatalities (Figure 1). Takeoff and climb accounted for 31 percent of the fatal accidents and 28 percent of the on-board fatalities.

Fifty-six percent (66) of the fatal accidents that occurred during the approach, landing or go-around phases involved a non-precision approach, according to CAA analysis, and 13 percent (15 accidents) occurred on at least the second attempt to land. In seven of the accidents in this category, there was insufficient information to determine whether the aircraft flew a precision or non-precision approach. Sixteen fatal accidents, or six percent of the total, occurred during a diversion following a problem, and 13 occurred while the crew was attempting to fly the airplane back to the departure airport.

Sufficient information was available for about 74 percent, or 185, of the 250 fatal accidents to determine primary causal factors, said CAA. While any number of causal factors may have been allocated for each fatal accident, only one was identified by CAA as the primary causal factor.

The CAA analysis showed that 129, or 52 percent, of the total fatal accidents involved an “airline-related” primary causal factor (Figure 2, p. 43). Thirty-two (13 percent) of the fatal accidents involved an ­airworthiness-related primary causal factor, such as system component failure, engine failure, design issues and maintenance, according to the report. Drilling down further, the most frequently identified primary causal factor was “flight crew handling/skill – flight handling,” which falls within the “airline-related” causal group, according to CAA’s taxonomy.

“Flight crew handling/skill – flight handling,” which CAA said generally related to events in which the aircraft was controllable but the “flight crews’ mishandling of the aircraft or poor manual flying skills lead to the catastrophic outcome,” was identified as the primary causal factor in 35, or 14 percent, of the fatal accidents, followed by “flight crew perception and decision making – omission of action or inappropriate action” (30 fatal accidents, 12 percent) and “flight crew situational awareness – lack of positional awareness – in air” (26 accidents, 10 percent). The top 10 primary causal factors accounted for 59 percent of all fatal accidents and 80 percent of those for which a primary cause was allocated (Table 1).

The CAA report also categorizes the 250 fatal accidents by aircraft class and nature of operation, among other factors. Jets were involved in 96 (38 percent) of the accidents, turboprops in half (125) and business jets in 29, or 12 percent (Figure 3). Jets were involved in an average of 10 fatal accidents per year during the study period, turboprops in 13 per year on average and business jets in three per year.

As would be expected because of the size of the aircraft, fatal accidents involving jets accounted for 78 percent of on-board fatalities during the decade examined. Accidents involving turboprops accounted for 21 percent of fatalities and business jets one percent.

Over the 10-year period, passenger flights were involved in 144 (57 percent) of the fatal accidents, followed by cargo flights at 77 accidents or 31 percent and ferry/positioning flights, 30 accidents or 12 percent (Figure 4). The total adds up to 251 instead of 250 because one of the fatal accidents was a midair collision between a passenger airplane and a cargo flight and was counted in each category, CAA said. Passenger flights were involved in 14 fatal accidents per year, cargo flights in eight and ferry/positioning flights in three.

Overall, 75 of the fatal accidents (30 percent), and 27 percent of the on-board fatalities occurred in Africa, followed by 22 percent of accidents and 31 percent of fatalities in Asia and the Middle East, and 17 percent of accidents and 19 percent of fatalities in Europe (Figure 5).² Twenty-eight percent of the fatal accidents involved African operators; 22 percent European operators; 18 percent North American operators; 17 percent Asian and Middle Eastern operators; 13 percent Caribbean, Central and South American operators; and 2 percent Oceanian operators.

As is common in the industry, the CAA also calculated fatal accident rates, but was careful to point out that the rates do not include fatal accidents involving business jets or ferry/positioning flights because consistent utilization data for these types of aircraft and operations are unavailable. With those exclusions, there were 205 fatal accidents during the 2002–2011 period and 6,983 on-board fatalities. The fatal accident rate per million flights was 0.6 and the fatal accident rate per million hours flown was 0.4 (Table 2).

Jets generated 78 percent of the flights and 89 percent of the flight hours during the study period and were involved in 45 percent of the fatal accidents. Turboprops accounted for 22 percent of the flights and 11 percent of the flight hours, but were involved in 55 percent of the fatal accidents (Table 3). “On average, the fatal accident rate for turboprops was four times that for jets, based on flights flown, and nine times greater when using hours flown as the rate measure,” the CAA said. The fatal accident rate per million flights for jets was 0.4, but 1.6 for turboprops. The jet fatal accident rate per million hours flown was 0.2, compared with 1.8 per million flight hours for turboprops. Jets had a greater fatality rate than turboprops (22.3) per million flights, but a lower fatality rate per million hours flown.

When looking at the nature of the flight operation (passenger versus cargo), passenger flights generated 94 percent of the flights flown and 93 percent of the flight hours and were involved in 65 percent of the fatal accidents. Cargo flights were involved in 36 percent of the fatal accidents. “On average, the fatal accident rate for cargo flights was eight times greater than for passenger flights, based on flights flown, and seven times greater when using flight hours as the rate of measure,” the report said (Table 4).

Broken down further, the data show that the fatal accident rate per million flights for turboprop cargo flights was 18 times greater than for jet passenger flights, and over 28 times greater when using hours flown as the exposure measure. “These aircraft class–nature of flight combinations represented the two extremes of the dataset in terms of safety performance,” the report said (Table 5).

Notes

1. Global Fatal Accident Review 2002 to 2011.
2. The U.K. CAA based its regions on those defined by the International Civil Aviation Organization Safety Indicators Study Group, but for the purposes of the study, the Asia and Middle East regions were combined, as were the Caribbean, Central America and South America regions.