Controlled flight into terrain accidents among commuter and air taxi operators in Alaska

Between 1990 and 1998, aviation accidents in Alaska caused 100 occupational pilot deaths (equivalent to 430/100,000 pilots/ year, approximately 86 times the overall U.S. worker fatality rate). Although Alaskan geography and climate increase aviation risks, many accidents were attributed to pilot error. While most accidents occurred during takeoff/landing, most fatalities resulted from Controlled Flight Into Terrain (CFIT). The purpose of this study was to examine risk factors for CFIT.

Using National Transportation Safety Board airplane accident data we identified CFIT from flight phase and event description fields, and calculated odds ratios for CFIT/non-CFIT accidents for visual conditions, aircraft features, and pilot experience.

Between 1991 and 1998, 351 single aircraft commuter and air taxi accidents occurred in Alaska; 59 (17%) were CFIT. Of 140 total fatalities, 82 (59%) occurred in 30 CFIT accidents. There was a twelve-fold risk for death in CFIT vs. non-CFIT accidents (OR = 12.42, 95% CI = 8.19-18.88). Accidents while flying Visual Flight Rules (VFR) into poor visibility were more likely CFIT than non-CFIT (Odds ratio = 46.06, Confidence Interval = 19.32-112.46), and caused 37% of all deaths. Additionally, flights in Instrument Meteorological Conditions (IMC) were 47 times more likely to be CFIT than non-CFIT. No risk for CFIT was shown for flight hours, number of engines, passenger presence, or pilot age. All CFIT were attributed to pilot error, often for continuing VFR into poor visibility.

CFIT caused most aviation deaths. Further research into human factors contributing to CFIT is needed. Implementation of global-positioning, ground-proximity/avoidance technology, might reduce CFIT incidence.