Ozbusdriver. CASA responded to the BASI See and Avoid report in 2001.
....and should ensure that unalerted see-an-avoid is never the sole means of separation for aircraft providing scheduled services."
CASA understands the intent of this recommendation but does not agree with its absolute form. The wording of the recommendation reflected its time and was prior to the 1995 Standards Australia AS/NZS4360 Risk Management Standard. CASA also understands that the use of the absolute "never" is not consistent with current ATSB practice.
To accept the absolute form of the recommendation would require the allocation of Class D or higher airspace wherever scheduled services operate. This would result in an allocation of resources that is not commensurate with risk.
ICAO Class E and G airspace specifically has no radio requirement for VFR aircraft. ICAO has introduced both of these classifications with the full knowledge of the limitations of see-and-avoid. ICAO makes no recommendation in relation to scheduled services not operating in these airspace classifications.
Overly discounting the effectiveness of see-and-avoid and devising unique procedures has itself led to unintended consequences that are unresolved. Pilots may scan significantly less and become over reliant on radio alerting through a concept known as diffusion of responsibility. The BASI report RP/93/01 (December 1993) and the continuing incident reports that are being filed listing near misses in mandatory radio Class E and G airspace may support this concern. CASA believes that radio alerting is only effective when the alerting area is small with readily identifiable reporting points so that the alert is specific.
The ATSB status? Closed - Accepted.