U.S. Navy Ejection Morbidity & Mortality : 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. Uniformed Services University of the Health Sciences *Naval Aviation Schools Command

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 ( USN) Collins et. al., ASEM 1997 ( USAF) Vasques et. al. ASEM 1999 ( SAF) Werner ASEM 1999 ( GAF)

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? USN Ejection Injury Odds & Trends

Methods: Case Series of all Naval Safety Center USN & USMC Class A Flight Mishap ejections FY 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 USN Ejection Injury Odds & Trends

Results: FY 1990 – 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 USN Ejection Injury Odds & Trends

USN Ejection Injury Odds & Trends Inside & Outside Envelope Odds of Injury Level “X” vs Not Injury Level “X”

USN Ejection Injury Odds & Trends USN Ejection Injury Odds & Trends Uninjured Odds Ratio, Inside Uninjured Injured (+fatal) Inside Envelope Outside Envelope OR = 3.63 [0.5495, 3.70] 95% CI Power = p-value = 0.945,  = 0.05

USN Ejection Injury Odds & Trends USN Ejection Injury Odds & Trends Minor Injury Odds Ratio, Outside Minor Injury Not a Minor Injury Outside Envelope 213 Inside Envelope OR = 0.48 [0.0451, ] 95% CI Minor injury inside envelope OR = 2.08 [0.1964, ] 95% CI Power = p-value = ,  = 0.05

USN Ejection Injury Odds & Trends USN Ejection Injury Odds & Trends Major Injury Odds Ratio, Outside Major Injury Not a Major Injury Outside Envelope 123 Inside Envelope OR = 2.02 [0.202, ] 95% CI Power = p-value = *,  = 0.05

USN Ejection Injury Odds & Trends USN Ejection Injury Odds & Trends Fatality Odds Ratio, Outside Fatality Not a Fatality Outside Envelope Inside Envelope OR = [102.67, ] 95% CI Power = p-value << 0.001*,  = 0.05

Trends : per FY since 1990 # of Ejections  # of Injuries & # of fatalities  Injury & fatality rates for inside the envelope  Fatality rate for outside the envelope  USN Ejection Injury Odds & Trends

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

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

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.

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.

Questions? USN Ejection Injury Odds & Trends LT Jim Hunt

Weakness: Odds are based on injury classification codes and envelopes as reported in Aeromedical Analysis & SIR appendices/forms. Some misclassifications seemed to exist in reports, mostly injuries. Not all injuries were specified, including Cause of Death. Strengths: Injury classification reporting errors were corrected. Differential reporting bias errors for envelopes were not included. USN Ejection Injury Odds & Trends

Future: The next look could refine fatalities & injuries specifically related to the ejection envelope. Could include differential envelope reporting bias numbers to increase the N for the crude estimate of envelope risk factor for injury and fatality.