ATSB analysis indicates no adverse safety trend since NAS stage 2b was introduced on 27 November 2003 based on the ATSB's preliminary review of its aviation safety occurrence database, including an examination of TCAS resolution advisory alerts.
Because of the significance of NAS airspace changes and public debate over the safety of their implementation, the ATSB has reviewed and categorised NAS-related occurrences and undertaken a comparative analysis of TCAS resolution advisory (RA) alerts in the 140 days from 27 November 2003 with 140 days a year earlier.
There were 37 RAs after NAS 2b was…