Recommendation

CASA's current processes for periodic revalidation of instrument
approaches specifically address pilot workload and other potential
hazards. 

The approach design and validation methodology adopted in
Australia is ICAO compliant (see Doc 8071 - in which Australia
participated in the

development) and uses GPS United States Federal Aviation
Administration TSO receivers. These standards have all been subject
to international (risk

assessment) review and acceptance during their development, and are
therefore not included in the approach validation process.

The validation requirements do necessitate the consideration of
other potential hazards (refer Doc 8071 and MOS). This process is
part of the

overall procedure design and implementation methodology as defined
by ICAO.

In accordance with CASR Part 173, CASA issues procedure design
authorisations and, procedure design certificates. Such
authorisations have been provided to officers of Airservices
Australia. CASA may also determine an instrument approach procedure
under CAR 178(6). CASA validates new approaches by confirming that
they meet the PANS - OPS criteria and test flying.

In the case of revalidation of an approach, CASA also test flies
the approach concentrating on the identification of changes in
physical obstacles, airspace, or traffic which may affect the
approach.

CASA has developed a draft Advisory Circular (AC) which contains
guidance, procedures and checklists to validate instrument
approaches. This draft AC also covers issues such as approach
fly-ability, and pilot workload (based on the standard of a
recently rated pilot).

The draft AC is being used as the basis for the revalidation of
a number of approaches. This project commenced in February, and to
date CASA has completed approximately 100 approaches.

A final version of the AC will be settled once the revalidation
project is completed and is expected to be made available to
industry at the end of 2008.

On 11 August 2008, CASA and Airservices staff flew the Runway 12
RNAV GNSS approach with an aircraft fitted with a Garmin 430w GPS
and TAWS-B. The first approach was flown using the 3.49 degree
profile on autopilot. No terrain or 'pull-up' warnings were
received. After flying the approach on profile, two lower than
profile approaches were flown, below the cloud base (around 2500')
along the laterally guided flight path. On each occasion the
terrain warning and pull up functions of the TAWS sounded well
before the significant ridges. It was also noted by the operating
pilot that the approach was no more difficult to fly than any other
he had experienced.

...

I have also attached, for your information, a more detailed
report with recommendations for further CASA action. I understand
that these outcomes have been communicated to your staff and that
it has been agreed that TAWS A warnings could be experienced on a
range of approaches besides RNAV GNSS depending on the aircraft
configuration and the nature of terrain in the vicinity and was
affected by any pilot decision to not fly the optimum profile as
published. This is not a circumstance unique to Lockhart River or
RNAV (GNSS) approaches.

...

Recommendations

...

4. Consideration be given to a CASA funded TAWS A to be fitted
to the Radiola (VH) conquest for CASA for project development
applications and CASA staff training.

CASA further advised that:

• CASA had published a number of articles regarding the use of
  stabilised approach techniques when flying non-precision
  approaches. CASA was also in the process of developing further
  educational material relating to the operation and use of terrain
  awareness warning system Class A (TAWS-A) equipment, with
  particular emphasis on the need for operators to ensure adequate
  pilot training in the characteristics of the equipment fitted to
  their aircraft, and operational practices that maximise the benefit
  of the equipment.
• CASA had purchased a set of TAWS-A equipment that is currently
  being fitted to a Cessna Conquest aircraft for use in approach
  validation. The effort will initially focus on revalidating
  approaches at aerodromes in the vicinity of steep, high terrain to
  determine the potential for terrain alerts. The information will
  then be used in the consideration of the priority for the design of
  approaches with vertical guidance (APV), or for the redesign of an
  approach where that would be beneficial and feasible.
• The new design for the Lockhart River Runway 12 RNAV (GNSS)
  approach is expected to be validated in early August 2009 using the
  TAWS-A equipped aircraft, and will be promulgated as soon as
  practical after the successful completion of that flight
  validation.

On 18 September 2009, Airservices Australia advised the ATSB
that the Lockhart River runway 12 RNAV (GNSS) non-precision
approach had been redesigned and flight validated. The flight
validation was conducted with a TAWS-A equipped aircraft and the
'the procedure did not trigger terrain warnings'. The new approach
will be published in the Aeronautical Information Publication
amendment effective 19 November 2009.

In response to the ATSB Safety Issue investigation AI-2007-010,
Airservices Australia advised the ATSB that Airservices would
redesign the Lockhart River Runway 12 RNAV (GNSS) non-precision
approach using the latest revision of the ICAO PANS-OPS procedures
that were released on 31 October 2008.

On 13 May 2009, Airservices Australia provided the ATSB with a
draft of a revised approach design. The redesigned approach had a
final approach path that was aligned with the runway (119° M),
which resulted in the approach moving to the south of the South Pap
ridge. The revised approach is currently being validated prior to
its approval for use.

In response to the ATSB Safety Issue investigation AI-2007-010,
CASA advised the ATSB that CASA would support Airservices in the
design and approval of the Lockhart River Runway 12 RNAV (GNSS)
non-precision approach to the latest revision of ICAO PANS-OPS.