In-flight upset - 154 km west of Learmonth, WA, 7 October 2008,

Statistical analyses 197 were done to compare the adult passengers on severalvariables. The main results were:• There was no difference between the seat belt use rate of males (59%) andfemales (55%).• The seat belt use rate appeared to increase with age, and the difference betweenpassengers aged 18 to 45 (43%) and passengers over 45 (67%) was statisticallysignificant.• Adult passengers from Asian countries had a significantly lower seat belt userate (39%) than other adult passengers (63%).• Adult passengers in the rear section had a lower seat belt use rate (44%) thanpassengers from the front and centre sections (64%). The proportion of adultpassengers aged 18 to 45 was higher in the rear section (63%) compared to thefront and centre sections (41%). The proportion of adult passengers from Asiancountries was also higher in the rear section (46%) compared to the front andcentre sections (26%).4.7.3 Situational factorsThe investigation attempted to obtain seat belt use data from other flights todetermine if seat belt use varied depending on situational factors, such as the timeof day or duration of the flight. The operator reported that it did not have any dataregarding passenger seat belt use rates during flights when the seat-belt sign was notilluminated. Two other operators in the Asia-Pacific region were also contacted, andboth reported that they had not collected any such information on seat beltcompliance. No relevant research studies were identified.Passenger surveys are occasionally conducted during aircraft occurrenceinvestigations. One previous survey conducted by the ATSB asked about seat beltuse during the cruise phase of flight. The occurrence was a depressurisation eventinvolving a Boeing 747-438, 475 km north-west of Manila Airport in thePhilippines on 25 July 2008. 198 The depressurisation event occurred about55 minutes into the flight. At the time a meal service was being conducted in theeconomy section and a drink service in other sections of the cabin. From the346 passengers on board, 152 questionnaire responses were obtained. Of thesepassengers, 127 reported they were seated with their seat belt fastened, 22 said theywere seated without their seat belt fastened, and two were not seated. The seat beltuse rate for these passengers was therefore 85%.The seat belt use rate during the 25 July 2008 occurrence was higher than for the7 October 2008 occurrence. This could be attributable to the time of the event in theflight, occurring soon after takeoff and prior to the meal service being completed. Incontrast, the 7 October 2008 occurrence occurred after the meal service and over3 hours into the flight.In addition to factors such as the time since takeoff, it could be expected that seatbelt use would be higher on flights where turbulence had been experienced. On the197Statistical comparisons were done using the χ 2 (Chi squared) test for independent groups. In thisreport, ‘statistically significant’ means that the chance of the difference being present due tochance alone was less than 5%.198See ATSB investigation report AO-2008-053 available at www.atsb.gov.au.- 183 -