This report follows a previous report published by the Australian Transport Safety Bureau (ATSB) in 2003 on airspace-related occurrences titled Airspace-Related Occurrences Involving Regular Public Transport and Charter Aircraft within Mandatory Broadcast Zones. The 2003 report provided a detailed examination of the ATSB's accident and incident data for airspace-related occurrences in Mandatory Broadcast Zones (MBZs), between 1994 and 2001. In recognition of changes in traffic levels, occurrence reporting rates and the classification of incidents following the enactment of the Transport Safety Investigation Act in 2003 (ATSB, 2003b), an update of the analyses was considered necessary.
The purpose of the current report was to examine occurrences associated with MBZs in Australia. Specifically, the objectives of the report were to:
- examine the number of occurrences involving General Aviation (GA) aircraft in addition to occurrences involving Regular Public Transport (RPT) aircraft that occurred in MBZ airspace from 2001 to 2004; and
- examine the number of occurrences involving GA aircraft and RPT aircraft that were associated with intentional and unintentional non-compliance with MBZ procedures from 2001 to 2004.
MBZ occurrences were identified using the ATSB aviation occurrence database and subsequently validated by two ATSB Senior Transport Safety Investigators. The occurrences were then examined according to three different criteria. The first criterion encompassed all airspace-related occurrences within MBZs. The second criterion related to only those occurrences where the pilot intentionally mis-complied with MBZ procedures. In contrast, the third criterion related to only those occurrences where the pilot unintentionally mis-complied with MBZ procedures.
In total, 257 airspace-related occurrences in MBZ airspace involving GA aircraft and RPT aircraft for 2001 - 2004 were identified. The highest number of occurrences took place in 2001 and were classified as a Category 5. The number of airspace-related occurrences declined from 3.9 in 2001 to 3.1 per 100,000 hours flown by GA and RPT aircraft in 2002 and remained at 3.1 for 2003 and 2004. These findings suggest that the number of MBZ airspace-related occurrences declined slightly over the four-year period. The findings contrast with those presented in the 2003 report (Figure 1, page 9), which showed an increase in airspace-related occurrences between 1994 and 2001 (ATSB, 2003a).
Of the airspace-related occurrences identified, 145 involved intentional non-compliance with MBZ procedures and 25 involved unintentional non-compliance with MBZ procedures. Most of the non-compliance occurrences were in 2001 and were classified as a Category 5. The number of intentional non-compliance occurrences decreased from 2.6 per 100,000 hours flown by GA and RPT aircraft in 2001 to 1.4 in 2004. This finding suggests that the number of occurrences involving non-compliance generally declined over the 2001 - 2004 period. In contrast, the rate for unintentional occurrences remained below 1 per 100,000 hours flown and did not appear to vary across the four-year period.
Overall, the findings suggest that the number of MBZ airspace-related occurrences in Australia between 2001 and 2004, including those specifically relating to non-compliance with MBZ procedures, was relatively low. Furthermore, the findings suggest that the rate of MBZ-related occurrences did not rise during this period. It may therefore be deduced that the risk due to MBZ-related occurrences did not increase. Importantly though, due to recent changes and potential inconsistencies in the reporting and recording of occurrences, the findings on which these conclusions are based need to be interpreted with caution.
|Type:||Research and Analysis Report|
|Publication date:||24 February 2006|