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Project AS 12/38 - Amendment of Part 139 MOS Chapter 11 concerning approval of aerodrome development that infringe on the clearance areas for airways facilities

Topic code: 
Airspace and Aerodromes
Project status: 
Closed

Closure notes

Project closed 18 December 2013.

Part 139 Manual of Standards (MOS) has been amended in accordance with the project objective.

Issue

CASR 139.165 provides that the operator of a certified aerodrome must ensure that the physical characteristics of the movement area (of an aerodrome) comply with the standards set out in the Manual of Standards for Part 139 (MOS139).

Paragraph 11.1.4 of MOS139 establishes the general requirements applicable to airways facilities for the assurance of the acceptable performance of each particular facility. Sub-paragraph 11.1.4.1 also provides that any potential infringement by an aerodrome operator on the siting criteria for existing or planned facilities is to be referred to Airservices Australia by the aerodrome operator. The responsibility of the aerodrome operator in that respect is further amplified in sub-paragraph 11.1.4.3, including the responsibility to ensure that Airservices Australia is consulted on proposed aerodrome works, developments or temporary constructions which may affect such airways facilities.

Paragraphs 11.1.6 to 11.1.15.3 inclusive of MOS139 set out the standards for siting requirements, including the clearance areas and the dimensions of restricted areas around the sites for airways facilities at certified or registered aerodromes. The types of airways facilities covered under the siting standards are navigation aid facilities, terminal area radar facilities and communication facilities used for aircraft control, guidance and for ATC. They take the form of specified siting requirements and the dimensions of restricted areas around the sites necessary to ensure that radio transmissions are not unacceptably affected by other aerodrome infrastructure, buildings, hangars, vehicles or personnel.

The relevant standards in MOS139 are generic in that they are based on acceptable operation at all locations under normal conditions. However, it is known by Airservices that depending on the location and the type of facility and the proposed aerodrome development, the dimensions of some of the restricted areas may be infringed without leading to unacceptable technical and/or operational affect to the functional performance of the facility.

There have been some occasions where an aerodrome operator has requested CASA for an exemption to the site clearance requirements in the MOS139 that were acceptable to Airservices Australia, but were not in compliance with the MOS139 standards. This means that in order to approve a development, CASA is forced to provide an exemption under CASR Part 11 for every individual development.

Airservices Australia, the sole certificate holder for the provision of airways facilities under CASR Part 171, possesses the capability to make technical and operational impact assessments of proposals by aerodrome operators that impact on the standard siting criteria for particular airways facilities. CASA does not have that capability itself and therefore must rely on Airservices for the advice.

CASA intends to retain the relevant standards of MOS139 as they preserve a conservative approach to protection of safety related services. However, where an aerodrome operator has consulted with and received the written agreement of Airservices Australia, the availability of a general approval in the MOS139 standards would mean that CASA does not have to make individual exemptions for every aerodrome development proposed by an aerodrome operator which may intrude on the standards.

This provision will be included in an amendment to MOS139 paragraph 11.1.4, subject to the following conditions:

Conditions: The general approval for an aerodrome operator to proceed with a development that infringes the published siting criteria would be subject to the following conditions:

  1. Non-compliance with or infringement of a MOS siting standard for any airways navigation, communication or radar facility included in MOS 139 at paragraphs 11.1.6 to 11.1.15.3 inclusive may only be permitted with the prior written agreement of Airservices Australia having been received by the aerodrome operator for each proposed aerodrome development.
  2. The aerodrome operator must retain the written agreement of Airservices Australia in keeping with statutory requirements for records retention and provide the written agreement to a CASA aerodrome inspector at the request of the inspector.

Safety Impact

Airways and Aerodromes Branch acknowledges that the existing standards in MOS139 are based on historically proven guidance material intended to allow development up to a defined boundary and known to not have a significant impact on the operation of the airways facilities.

Having this material as a standard provides good protection of the integrity and safety of the airways facility.

However, the actual impact of any particular development can be ascertained by an appropriate engineering and operational analysis or by measurement with suitably qualified people/tools. This exemption gives the CASR 139 certificate holder the ability to proceed with a development that may infringe the standards provided it has the written agreement of Airservices Australia on the basis of evidence that the operational impact (if any) is acceptably safe.

Airservices has a Safety Management System (SMS) to assure the integrity of the process followed and CASA routinely audits Airservices compliance against its SMS.

Project Objective

The objective to is to amend paragraph 11.1.4 of Part 139 MOS to provide that an aerodrome operator may proceed with an aerodrome development that infringes a MOS siting standard for any airways communication, navigation or radar facility included in Part 139 MOS at paragraphs 11.1.6 to 11.1.15.3 inclusive with the written agreement of Airservices Australia.

Status

This project was approved by Peter Boyd Executive Manager Standards Division on 31 October 2012.

Rules affected

Part 139 MOS

Project management

Project Leader: Brian Harris

Project Sponsor: Malcolm McGregor, A/g Executive Manager Airspace & Aerodrome Regulation Division

Standards Officer: TBA

Project Priority

High

Airspace and Infrastructure Users Group (SCC)

Airspace and Infrastructure Users Group Sub-committee

History

Title Details Date
Consultation updates in 2014
Project AS 12/38 - Amendment of Part 139 MOS Chapter 11 concerning approval of aerodrome development that infringe on the clearance areas for airways facilities This project is now closed

Refer to the project closure notes for further information.
6 Jan 2014
Consultation updates in 2013
NFC 139/07 - Aerodromes - Amendments to Part 139 MOS Chapter 11 This final NFC has been published. 17 Dec 2013
NPC 139/07 - Proposed Amendment to Manual of Standards (MOS) Part 139 - Aerodromes - Chapter 11 Comments close of business 15 May 2013. 19 Mar 2013
Consultation updates in 2012
Project AS 12/38 - Amendment of Part 139 MOS Chapter 11 concerning approval of aerodrome development that infringe on the clearance areas for airways facilities Project approved. 7 Nov 2012