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U.S. Navy Ejection Morbidity & Mortality 1990-2004:

U.S. Navy Ejection Morbidity & Mortality 1990-2004:. A first look at the odds of injury and fatality during ejection, and the trends for each injury level. Presented at the 77 th Scientific Meeting of Aerospace Medicine Association. Hunt, J.C. ,* M.P.H., and Johanson, D.C., Ph.D.

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U.S. Navy Ejection Morbidity & Mortality 1990-2004:

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  1. U.S. Navy Ejection Morbidity & Mortality1990-2004: A first look at the odds of injury and fatality during ejection, and the trends for each injury level. Presented at the 77th Scientific Meeting of Aerospace Medicine Association Hunt, J.C.,* M.P.H., and Johanson, D.C., Ph.D. Uniformed Services University of the Health Sciences *Naval Aviation Schools Command

  2. USN Ejection Injury Odds & Trends Introduction: Ejection systems allow escape. The ejection seat envelope defines safe operating limits. Previous studies show survivability improvements Yacavone et. al., ASEM 1992 (1977-1990 USN) Collins et. al., ASEM 1997 (1981-1995 USAF) Vasques et. al. ASEM 1999 (1979-1995 SAF) Werner ASEM 1999 (1981-1997 GAF)

  3. USN Ejection Injury Odds & Trends Research Questions: What are the odds ratios for each injury level outcome with envelope as a risk factor? What are the rates for each injury level & fatality adjusted for declining annual flight hours?

  4. USN Ejection Injury Odds & Trends Methods: Case Series of all Naval Safety Center USN & USMC Class A Flight Mishap ejections FY1990 - FY2004 Inclusion criteria: • 1 aircrew escaped & envelope determined Injury Levels: None, Minor, Major & Fatal Major: internal organ, fracture, dislocation, >5% burn, 2º sprain/strain, LOC >1 min., 5 lost work days,… Counts from SPSS & trends from Microsoft Excel

  5. USN Ejection Injury Odds & Trends Results: FY 1990 – 2004 447 ejection events 384 (85.9%)survivors, 14.1% Fatal 348 (90.6 %) survivors injured, 61.8% minor injury, 15.8% Major 398 (89.7%) ejection envelopes determined 356 (79.5%) ejections were inside the envelope

  6. 9.5 4.167 2.02 .5 .089 .248 .047 .024 USN Ejection Injury Odds & TrendsInside & Outside Envelope Odds of Injury Level “X” vs Not Injury Level “X”

  7. USN Ejection Injury Odds & Trends Uninjured Odds Ratio, Inside OR = 3.63 [0.5495, 3.70] 95% CI Power = 0.8637 p-value = 0.945,  = 0.05

  8. USN Ejection Injury Odds & Trends Minor Injury Odds Ratio, Outside OR = 0.48 [0.0451, 5.1091] 95% CI Minor injury inside envelope OR = 2.08 [0.1964, 22.0256] 95% CI Power = 0.1379 p-value = 0.6005,  = 0.05

  9. USN Ejection Injury Odds & Trends Major Injury Odds Ratio, Outside OR = 2.02 [0.202, 20.197] 95% CI Power = 0.1379 p-value = 0.03644*,  = 0.05

  10. USN Ejection Injury Odds & Trends Fatality Odds Ratio, Outside OR = 201.88 [102.67, 396.97] 95% CI Power = 0.8637 p-value << 0.001*,  = 0.05

  11. USN Ejection Injury Odds & Trends Injury Rates for Safe Ejection Envelope Injuries/100,000 FH

  12. USN Ejection Injury Odds & Trends Injury rates for Outside Safe Ejection Envelope Injuries/100,000 FH

  13. USN Ejection Injury Odds & Trends Conclusions: 79.5% ejections were w/in the envelope. When outside envelope Major injury odds were 2 x greater, Fatality odds were 202 x greater. *Envelope was a statistically significant risk factor for Major injury & fatality.

  14. USN Ejection Injury Odds & Trends Conclusions (continued): Minor injury w/in the envelope were 2x > outside. …Ejection injury risk is worthwhile. Generally, all levels of injury have  over the years. Injury rates w/in the envelope have  , despite  flight hours (exposure). …Survivability has improved. …Envelopes may have expanded.

  15. USN Ejection Injury Odds & Trends Questions? LT Jim Hunt james.c.hunt@navy.mil 850-452-3241

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