Commercial aircraft involved in high altitude operations are
generally pressurised to protect the occupants from the adverse
effects of hypoxia, decompression illness and hypothermia. Failure
of the pressurisation system is a potential threat to flight
safety. The purpose of this study was to determine the prevalence
and consequences of aircraft decompression events in Australian
civil aviation. The aim was to document the prevalence, nature,
type, degree and extent of decompression events in Australian civil
aviation, as well as the consequences of such events, especially
hypoxia and pressure-related medical effects. A search of all
incidents and accidents on the ATSB database was made for
pressurisation failure events between 1 January 1975 and 31 March
2006. A total of 517 pressurisation failure events were found (two
accidents, eight serious incidents and 507 incidents). Only one
pressurisation failure event was fatal (0.2 per cent of the total
events). Hypoxia was reported in four of the events, and ear
barotrauma was also reported in four events, due to the subsequent
emergency descent. A total of 10 events involved death, hypoxia or
minor injury. Mechanical factors were responsible for the majority
of pressurisation system failures (73 per cent). The average rate
of cabin pressure change was 1,700 feet per minute, and the average
maximum cabin altitude reached was 10,978 feet. In general, the
results of this study show that there is a high chance of surviving
a pressurisation system failure, provided that the failure is
recognised and the corresponding emergency procedures are carried
out expeditiously. Aircrew should maintain a high level of
vigilance with respect to the potential hazards of cabin
pressurisation system failure.