Yandong Qiang

Pilot error in air carrier mishaps: longitudinal trends among 558 reports, 1983-2002

BACKGROUND Many interventions have been implemented in recent decades to reduce pilot error in flight operations. This study aims to identify longitudinal trends in the prevalence and patterns of pilot error and other factors in U.S. air carrier mishaps. METHOD National Transportation Safety Board investigation reports were examined for 558 air carrier mishaps during 1983-2002. Pilot errors and circumstances of mishaps were described and categorized. Rates were calculated per 10 million flights. RESULTS The overall mishap rate remained fairly stable, but the proportion of mishaps involving pilot error decreased from 42% in 1983-87 to 25% in 1998-2002, a 40% reduction. The rate of mishaps related to poor decisions declined from 6.2 to 1.8 per 10 million flights, a 71% reduction; much of this decrease was due to a 76% reduction in poor decisions related to weather. Mishandling wind or runway conditions declined by 78%. The rate of mishaps involving poor crew interaction declined by 68%. Mishaps during takeoff declined by 70%, from 5.3 to 1.6 per 10 million flights. The latter reduction was offset by an increase in mishaps while the aircraft was standing, from 2.5 to 6.0 per 10 million flights, and during pushback, which increased from 0 to 3.1 per 10 million flights. CONCLUSIONS Reductions in pilot errors involving decision making and crew coordination are important trends that may reflect improvements in training and technological advances that facilitate good decisions. Mishaps while aircraft are standing and during pushback have increased and deserve special attention.

Age, Flight Experience, and Violation Risk in Mature Commuter and Air Taxi Pilots

Violation of Federal Aviation Regulations has been identified as a risk factor for pilot involvement in aviation crashes. However, the associations among violations, flight experience, and pilot age have not been well studied. In this study, we aimed to examine risk of violation in relation to pilot age and other pilot characteristics based on exposure to flight in a fixed birth cohort of 3,306 commuter air carrier and air taxi pilots who in 1987 were aged 45 to 54 years. We merged different data files from the National Transportation Safety Board and the Federal Aviation Administration for the years 1987 to 1997, and we analyzed violation rates per pilot flight hour in relation to total flight hours at baseline and pilot age at time of violation. During the 11-year follow-up period, a total of 12.9 million cumulative flight hours and 71 violations were recorded, yielding a rate of 5.5 violations per million pilot flight hours. Violation rate increased significantly with age from age 40 to the late 50s. Pilots who were 50 to 54 years old at baseline experienced almost twice the rate of violation involvement as pilots who were 45 to 49 years old at baseline. Total flight time at baseline, an indicator of flight experience, showed a significant protective effect against risk of violation. With adjustments for age, pilots who had 5,000 to 9,999 hr of total flight time at baseline were at significantly lower risk of violation than their less experienced counterparts (relative risk 0.43; 95% confidence interval 0.19 to 0.85). Flight experience showed a diminishing protective effect after pilots reached 10,000 hr of total flight time.

Mortality risk in a birth cohort of commuter air carrier and air taxi pilots

Commuter and air taxi pilots have higher work-related death rates than most other occupational groups. In this longitudinal study, the authors examined the mortality in a cohort of 3263 commuter and air taxi pilots. With adjustment for age, proportional hazards modeling revealed that termination or downgrading of medical certificates during the 11-year follow-up was associated with a significantly increased risk of overall mortality (relative risk, 2.32; 95% confidence interval [CI] = 1.43–3.77). Relative to the general population with similar demographic characteristics, commuter air carrier and air taxi pilots had significantly lower overall mortality (standard mortality ratio [SMR], 0.36; 95% CI = 0.32–0.41) and mortality from cardiovascular diseases (SMR, 0.18, 95% CI = 0.15–0.22), but considerably higher mortality from aviation crashes (SMR, 128.88; 95% CI = 6.35–2624.36). The results indicate that the current medical certification system is effective in maintaining a healthy pilot workforce.

Crash Rates of Scheduled Commuter and Air Carrier Flights Before and After a Regulatory Change

INTRODUCTION In 1997, in an effort to reduce the crash rate of scheduled commuter flights, the FAA required aircraft with 10-30 passenger seats to operate under stricter rules. Training and other requirements of 14 CFR Part 121 rules were applied to these midsize commuters, which previously had operated under the less strict Part 135 rules. Published crash rates obscured changes related to aircraft size. This research was undertaken to determine whether the rule change affected crash rates of aircraft with 10-30 passenger seats. METHOD We determined the number of passenger seats on each Part 135 or Part 121 aircraft that crashed between 1983 and 2007. For aircraft with < 10, 10-30, and > 30 seats, we estimated the numbers of departures and crash rates, adjusting for changes in total departures and numbers of in-service aircraft. RESULTS The Part 135 crash rate tripled in 1997 when commuters with 10-30 seats were excluded, reflecting the administrative change. However, the crash rate of aircraft with 10-30 passenger seats began to decline 4 yr before the rule change; thereafter, their rate was lower than for larger aircraft. The fleet size of aircraft with 10-30 passenger seats increased from 1983 to 1997, then declined as they were replaced with larger aircraft in response to the rule change. DISCUSSION No effect of the rule change on crash rates of 10-30-seat aircraft was apparent. The decline in their crash rates began before the rule change and may have been related to the 1992 requirement for ground proximity warning devices.

Hearing Deficit in a Birth Cohort of U.S. Male Commuter Air Carrier and Air Taxi Pilots

PURPOSE Long-term exposure to multiple risk factors in aviation may place pilots at excess risk of developing hearing deficits. We examined the incidence and risk factors for hearing deficit in a birth cohort of male commuter and air taxi pilots. METHODS The subjects (N = 3019), who were 45-54 yr of age and held Class I medical certificates in 1987, were followed up from 1987 to 1997 through the medical certification system of the Federal Aviation Administration (FAA). In this study, hearing deficit refers to the FAA pathology code 220 (defective hearing, deafness, not elsewhere classified). Poisson regression modeling based on generalized estimation equations was used to assess the associations between pilot characteristics and the risk of developing hearing deficit. RESULTS The 10-yr follow-up accumulated a total of 20,671 person-years and 574 incident cases of hearing deficit, yielding an incidence rate of 27.8 per 1000 person-years. Compared with age 45-49 yr, the risk of developing hearing deficit at age 50-54 yr, 55-59 yr, and 60-64 yr increased by 12% [adjusted relative risk (RR) 1.12, 95% confidence interval (CI) 0.98-1.30], 34% (RR 1.34, 95% CI 1.13-1.59), and 79% (RR 1.79, 95% CI 1.20-2.67), respectively. CONCLUSIONS Hearing deficit is prevalent among commuter air carrier and air taxi pilots and the risk of hearing deficit increases progressively with pilot age. Effective programs for preventing excess hearing loss in the pilot population are warranted.

Pilot Age and Geographic Region of Commuter and Air Taxi Crashes: a Case-Control Study

BACKGROUND Previous studies of major airline and general aviation crashes have identified a host of risk factors. We examined risk factors related to crashes involving commuter air carrier and air taxi flights. METHODS A matched case-control design was applied to assess the association of pilot age, total flight time, and geographic region with commuter air carrier and air taxi crashes (14 CFR Part 135) from 1983-2002 in the United States. A total of 2033 commuter air carrier or air taxi crashes from the National Transportation Safety Board aviation crash database were identified as eligible cases. Controls were randomly selected incidents from the Federal Aviation Administrations (FAA) aviation incident database coded under Part 135 operation. RESULTS Relative to controls, commuter air carrier and air taxi crashes were less likely to occur in pilots under 30 yr of age (adjusted odds ratio 0.68, 95% confidence interval 0.54-0.88) after adjusting for geographic region and total flight time. With adjustment for pilot age and total flight time, the commuter air carrier and air taxi crashes with pilot error were nearly 13 times as likely to be in Alaska as their matched controls (adjusted odds ratio 12.84, 95% confidence interval 5.24-31.45). CONCLUSIONS These results suggest that pilot age may be associated with risk of crash involvement in Part 135 operations. The excess crash risk in Alaska with or without pilot error underscores the importance of environmental hazards in flight safety.

Geographic Region, Weather, Pilot Age and Air Carrier Crashes: a Case-Control Study

BACKGROUND Information about risk factors of aviation crashes is crucial for developing effective intervention programs. Previous studies assessing factors associated with crash risk were conducted primarily in general aviation, air taxis, and commuter air carriers. METHODS A matched case-control design was used to examine the associations of geographic region, basic weather condition, and pilot age with the risk of air carrier (14 CFR Part 121) crash involvement. Cases (N = 373) were air carrier crashes involving aircraft made by Boeing, McDonnell Douglas, and Airbus recorded in the National Transportation Safety Boards aviation crash database during 1983 through 2002, and controls (N = 746) were air carrier incidents involving aircraft of the same three makes selected at random from the Federal Aviation Administrations aviation incident database. Each case was matched with two controls on the calendar year when the index crash occurred. Conditional logistic regression was used for statistical analysis. RESULTS With adjustment for basic weather condition, pilot age, and total flight time, the risk of air carrier crashes in Alaska was more than three times the risk for other regions ladjusted odds ratio (OR) 3.18, 95% confidence interval (CI) 1.35-7.49]. Instrument meteorological conditions were associated with an increased risk for air carrier crashes involving pilot error (adjusted OR 2.26, 95% CI 1.15-4.44) and a decreased risk for air carrier crashes without pilot error (adjusted OR 0.60, 95% CI 0.37-0.96). Neither pilot age nor total flight time were significantly associated with the risk of air carrier crashes. CONCLUSIONS The excess risk of air carrier crashes in Alaska and the effect of adverse weather on pilot-error crashes underscore the importance of environmental hazards in flight safety.