Tuesday, March 30 2010
Operations Manager, Office of Airspace Regulation
Civil Aviation Safety Authority
GPO Box 2005
CANBERRA ACT 2601
CC: Executive Manager, Airspace and Aerodrome Regulation
Re: Proposed Airspace Classification – Broome (OAR 192/09) and Karratha (193/09)
Dear Graeme,
Thank you for the opportunity to provide feedback on the airspace classification proposals for Karratha and Broome. As the professional organisation representing Australian Air Traffic Controllers, Civil Air has a number of points we would like to raise with respect to the proposed airspace models:
Class D to A025 with E Airspace Above
In Civil Air's view, this model is the least desirable for Broome and Karratha. The restriction of Class D airspace is such that it will not encapsulate all instrument approaches and thus ensure separation with VFR aircraft while aircraft are in the critical final stages of flight. IFR aircraft may also be required to monitor multiple frequencies during a period of high cockpit workload during their approach. With the small lateral boundaries of the Class D zone, VFR aircraft will be quite close to the aerodrome before they will be required to call for a clearance to enter control area. This gives the controller less time to evaluate, plan and implement a sequence, and ensure separation from other arriving and departing aircraft. VFR aircraft will be able to operate directly over the aerodrome at relatively a low level without requiring a clearance, giving faster moving traffic less time to "See and Avoid". This is a particular issue for high performance departures.
Class D to A045 with E Airspace Above
This solution provides increased margin as the Class D portion of the airspace will encapsulate aircraft manoeuvring for instrument approaches, and VFR aircraft will be required to call the tower earlier for a clearance to enter the control zone. This provides the tower controller increased time to arrange their sequence of aircraft, and more room to achieve the required separation but is still limited in the same manner as the proposal for D to A025, albeit with increased margins.
Class E above D - General Comments
Civil Air has concerns regarding the use of Class E airspace above Class D. The premise of E above D at Broome and Karratha is predicated upon an improvement in service level over existing Class G. Whilst demonstrably an improvement, it ignores practicalities of actual airspace management and, in our view, ignores the “As Low As Reasonably Practical” (ALARP) principle of risk management applied almost universally in aviation studies nationally.
In terms of airspace management, the modelling of C over D, as currently provided at all regional towers, offers improved separation integrity and virtually no additional operational costs to either the services provider or airspace users. Under ALARP it is impossible to justify E over D on either cost or safety basis when measured against the current C over D. It would be an untenable position for the Office of Airspace Regulation (OAR) to mandate a lower level of airspace, when a higher level of airspace is available for no additional cost. OAR would then risk being accused of putting ideology ahead of safety.
E over D introduces a new airspace model not in use elsewhere in Australia. This departure from accepted practice introduces a variation upon the standard operating procedures at all regional towers across Australia. It is also contrary to the provision of services under US NAS
(Part 139 Class 1 Airports licensed for Scheduled Air Carrier with >30 pax seat capacity) in respect of airspace modelling. In most scenarios these operations are conducted under a C over D model.
VFR aircraft operating in Class E airspace will be unknown to both the controllers in the local tower, and Enroute centres in Brisbane and Melbourne. Separation between VFR aircraft in the Class E airspace and IFR aircraft arriving and departing from these locations will rely upon "Unalerted See and Avoid" procedures, which greatly increases collision risk, particularly considering the different operating speeds of typical VFR aircraft and the jet or high capacity/performance RPT turbo-prop aircraft which typically operate into Broome and Karratha. Whilst ACAS will provide some defence it is Civil Air’s view that ACAS should not be considered a mitigator in airspace design as it is intended as a last line of defence. Alerted “See and Avoid” is predicated upon surveillance availability. In the case of Broome and Karratha the only prospect of surveillance is that of ADS-B and unfortunately penetration of ADS-B Out fitment in the GA fleet is limited at best.
E over D arrangements during Tower Closure
Operations in Class E require continuous two-way communications and, for aircraft descending into deactive tower airspace (Class G services), there is often pressure to make the change to CTAF at an early stage. For single VHF aircraft this means either non-compliance with maintaining comms on the appropriate Area VHF or, in the case of low level transition to G, obtaining CTAF traffic either during the approach or with limited reaction time.
Class D to A085 controlled by D Tower
An alternative that may produce a better cost/benefit result than E over D is establishing Class D airspace up to A085 controlled from the tower. This also has benefits for pilot and ATC workload management. The tower controller can utilise visual and geographic standards not available to Enroute controllers to separate VFR traffic from IFR, and allows for a more efficient movement of aircraft to and from the aerodrome. VFR aircraft within a reasonable distance of the aerodrome will be "known" to the Tower controller, and their separation ensured from IFR aircraft. This model could then be considered at other locations across Australia.
Civil Air's preference remains the use of Class C airspace above Class D towers as currently used at all D towers in Australia. Outside tower hours of operations the Class C steps below A085 should be deactivated. This provides standardisation of airspace architecture across Australia. Civil Air believes that this model of airspace represents the best mix between efficiency, equity of airspace, and safety.
Please do not hesitate to contact us for further information or expansion of any issues raised herein.
Sincerely,
Civil Air