Explanatory Statement
Civil Aviation Regulations 1988
Instructions amendment — use of RNAV (GNSS) approaches by RNP capable aircraft
Legislation
Section 98 of the Civil Aviation Act 1988 (the Act) provides that the Governor-General may make regulations for the purposes of the Act and in relation to the safety of air navigation.
Under subregulation 179A (1) of the Civil Aviation Regulations 1988 (CAR 1988), CASA may issue instructions in relation to Instrument Flight Rules (I.F.R.) flights specifying the method by which an aircraft is to be navigated and how a positive position fix is to be obtained.
Instrument CASA 404/05, issued under subregulation 179A (1), provides instructions as to how a pilot in command of an aircraft operating under the I.F.R. may use the Global Positioning System (GPS). Among other things, the instrument details the procedures for using GPS for carrying out non‑precision approaches, now referred to as RNAV (GNSS) procedures. It specifies the navigational equipment that must be installed.
ICAO rule changes
It is Australian aviation policy that instrument flight procedures should conform to the International Civil Aviation Organization (ICAO) design rules (ICAO Document 8168, commonly referred to as PANS‑OPS). Approximately 450 RNAV (GNSS) approaches designed in accordance with PANS‑OPS have been commissioned at 260 aerodromes across Australia. Those procedures are designed to be flown by aircraft equipped with self-contained GPS receivers and operated in accordance with CASA 404/05.
However, most modern Australian turbo‑jet airline aircraft are equipped with computerised flight management systems (FMS) that are more sophisticated than the GNSS navigation equipment mentioned in CASA 404/05. Such aircraft use GNSS positioning to update multiple inertial reference systems (IRS) employing self‑contained laser guided gyroscopes. These navigation systems are designed to comply with Required Navigation Performance (RNP) standards, and the operating procedures and cockpit displays are related to the RNP capability of the aircraft rather than to a specific GNSS receiver used by other less sophisticated aircraft.
On 25 November 2004, ICAO amended the criteria for RNP approach procedure design to reduce the obstacle clearance widths for RNP procedures. For aircraft capable of RNP 0.30, the new ICAO criteria require a lesser obstacle clearance area than is the case for aircraft using the “basic” GNSS receivers on which current RNAV (GNSS) approach procedures are based. Consequently, all existing RNAV (GNSS) approach procedures can now be flown by RNP 0.30 capable aircraft without further analysis or design of the instrument approach procedure.
Purpose of the amendment
Although equipped with more sophisticated navigation systems, modern airline aircraft are not directly compatible with the relatively simple Australian airworthiness requirements that apply to the use of GNSS by general aviation aircraft. Consequently, special evaluation of each aircraft type has been necessary to approve FMS equipped airline aircraft with GNSS updating capability (e.g. B737NG) to conduct RNAV (GNSS) approach procedures. Approvals have been given to Qantas Airways Ltd (Qantas) and Virgin Blue Airlines Pty Ltd (Virgin Blue) on this basis, but the process of evaluation and approval is complex and resource intensive.
With the change to the ICAO design rules, it is now possible to approve FMS equipped aircraft to conduct RNAV (GNSS) approach procedures on the basis of their RNP capability without the need for individual type approval.
Such approvals were issued to Qantas and Virgin Blue in CASA 189/05 and CASA 369/05, respectively.
CASA 189/05 referred to CASA 112/03, issued under subregulation 179A (1), as containing the standard instructions on how a pilot in command of an aircraft operating under the I.F.R. may use the Global Positioning System (GPS) and, therefore, with which the operator need not comply as long as it complied with CASA’s alternative instructions in the approval.
CASA 112/03 was in force at the time CASA 189/05 was made. However, in November 2005, CASA 404/05 revoked and replaced CASA 112/03 to provide updated standard instructions as to how a pilot in command under the I.F.R. may use the GPS.
To ensure that CASA 189/05 operates without unforeseen effects arising from that revocation, it is necessary to refer to CASA 404/05 as the instructions with which Qantas need not comply as long as Qantas complies with the terms of CASA 189/05. The problem does not arise for CASA 369/05.
Legislative Instruments Act
Subregulation 179A (3A) of CAR 1988 declares instructions to be a disallowable instrument. Under subparagraph 6 (d) (i) of the Legislative Instruments Act 2003 (the LIA), an instrument is a legislative instrument for section 5 of the LIA if it is declared to be a disallowable instrument in legislation in force before the commencement of the LIA. The amendment to the instructions is, therefore, a legislative instrument and is subject to tabling and disallowance in the Parliament under sections 38 and 42 of the LIA.
Consultation under section 17 of the LIA has not been undertaken in this case. The instrument is necessary to ensure that CASA 189/05 operates without unforeseen effects arising from the revocation of CASA 112/03.
The instrument commences on the day after it is registered and stops having effect at the end of July 2008.
The exemption has been made by the Deputy Chief Executive and Chief Operating Officer, a delegate of CASA, under subregulation 7 (1) of CAR 1988.
[Instrument number CASA 172/06]