Accidents are the events as defined by the ADREP Occurrence Class Taxonomy, limited to commercial scheduled flights and aircraft with a MTOW over 2550 kg. The number of accidents has been extracted from the ICAO ADREP/ECCAIRS database.
The global accident rate average (IAMA) was reinitialized on 1st of January 2005 using data from 01/01/2000 to 31/12/2004. No significant increase or decrease was recorded since then, making the IAMA a straight line. The upper band was busted once in 2005, however this bust was not confirmed in 2006, inducing that this increase was a one-time event and does not indicate any trend change.
The bandwidth is well within acceptable limits and assures ICAO that the indicator is valid and may be used to detect significant upward or downward trends. The bandwidth or volatility has even decreased in 2009, allowing for more precise future measurements.