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OS 09/09 - Improving the metric conversion accuracy of 19,000 pounds Maximum Take Off Weight (MTOW) in current and future Australian legislation

Topic code: 
Flight Operations
Project status: 

Closure notes

Civil Aviation Order 82.3 Amendment Order (No. 1) 2011 was made on 21 June 2011 by the Director of Aviation Safety. The amendment was registered on FRLI - F2011L01197 on 21 June 2011.


Section 82.3 of the Civil Aviation Orders (CAOs) is titled "Conditions on Air Operators' Certificates authorising regular public transport operations in other than high capacity aircraft". In paragraph 6.1c of CAO 82.3, a Maximum Take Off Weight (MTOW) of 8,640 kilograms is published. This figure has been derived from the Commuter certification category weight limit of 19,000 pounds, and appears to have been calculated using a conversion factor of about 2.2.

If the conversion of 19,000 pounds is calculated using a more accurate factor of 2.2046 (from the General Conversions table published in ERSA, 12 March 2009 edition, page GEN-CON-3), the resulting figure is very close to 8,618 kilograms. The EU's CS23 and Transport Canada both use 8,618 kilograms MTOW in their documentation.

Harmonising Australia's metric conversion of 19,000 pounds with that of other leading international aviation nations has merit on the grounds of technical accuracy and certification compatibility. There are currently no aircraft on Australia's Civil Aircraft Register that have an MTOW between 8,618 and 8,640 kilograms, and thus the impact of this proposed change on the aviation community is judged to be negligible.


The objective of this project is to change all references to 8,640 kilograms MTOW, in current and proposed Australian aviation legislation, to 8,618 kilograms.

As the proposed change is minor machinery in nature and the impact on the aviation community is judged as negligible, consultation via the (i) SCC, (ii) Operational Standards Subcommittee and (iii) Certification Standards Subcommittee forums is deemed sufficient to meet CASA's consultation obligations to affected stakeholders.


This project was approved by Peter Boyd, Executive Manager Standards Development and Future Technology, on 13 July 2009

Project management

Project Leader: Gareth Davey
Project Sponsor: Peter Boyd, Executive Manager, Standards Development and Future Technology
Standards Development Programme Manager: Nick Fisher