**3. Results**

The number of fatal aviation accidents and relative risks of the likelihood of pilot AAS being due to suicide three years after 11 September 2001, calculated for each year separately, is presented in Table 1. All pilots who died were male. The RR was 3.68 in the first year and decreased close to 1.0 in the third year. Only the observation for the first year was statistically significant.

**Table 1.** The number and the risk ratios of pilot aircraft-assisted suicides five years before and three years after 11 September 2001, in the U.S.


FRQ = frequency.

Altogether 23 fatal aviation accident reports were obtained with the specified search words. All index cases were identified with the search word "suicide", search words "homicide-suicide", or "murder-suicide" did not yield any additional index case incidents. Fourteen of these incidents were caused by a pilot's or co-pilot's suicidal act according to NTSB accident investigations, and these incidents are described in detail in Table 2. All the incidents were operationally related to general aviation, although three pilots had also Class I (commercial pilot) medical certification even though they were not flying commercial aircraft at the time of the suicide crash. It should be noted that three of the deceased pilots were also flight instructors. Altogether fourteen pilots or student pilots died in these incidents. Their ages ranged from 15 to 69 years. Eight of these aircraft-assisted suicides occurred after 11 September 2001; four within the first year, three during the second year, and one in the third year, while six aircraft-assisted suicides took place during the five-year-period before it (see timeline in Figure 1). NTSB causes of death for excluded cases in this search were: four undetermined causes of fatal aviation accidents, two related to psychological problems (drugs or alcohol were mentioned at least as a contributing factor), in two reports weather conditions were mentioned, and in one case death occurred due to a passenger's suicidal act.

**Figure 1.** Timeline of aircraft-assisted pilot suicides five years before and three years after 11 September 2001. Red arrows indicate aircraft assisted suicides.



**Table 2.** *Cont.*

\* Class 1 = Airline Transport Pilot; 2 = Commercial Pilot; 3 = Private or Recreational Pilot; \*\* NTSB = National Transportation Safety Board.
