Recommendation

I refer to the ATSB investigation report into the May 2002
accident at Bankstown airport. Specifically, I refer to
recommendation 20040056 and our considerations of this
matter.



While to the uninformed, the recommendation looks to be innocuous,
it involves some fairly complex issues and can not be easily or
quickly dealt with.

The recommendation involves two separate issues, the estimate of
the midair collision risk at the major GA airports, and the
identification of acceptable risk criteria.



Apart from simply plucking a number out of the air, the only way we
can effectively estimate the midair collision risk is to develop a
mathematical model that could be applied to the major GA airports.
The model would have to be tailor made to cater to the specific
environment, procedures and traffic mix found at those airports and
would involve a number of assumptions and estimates.



Collecting the data to input to a collision risk model of the type
referred to above would also be difficult, as the recommendation
does not distinguish between aircraft operations while the towers
are manned (GAAP), and operations during the time the towers are
closed (MBZ). We would have to undertake special out of hours
aircraft activity monitoring and develop the model in such a way
that it could cater to both types of operations.



The matter of identifying appropriate acceptable risk criteria, is
a slightly easier issue to deal with, but has one draw back. As you
are aware, we do not currently accept the proposed CASA acceptable
risk criteria as we believe it has particular technical problems.
We could, and probably will develop our own acceptable risk
criteria, however, this will leave us with a criteria that has
little independence. We will discuss this matter further with
CASA.



From the internal discussions we have had so far, we have concluded
that employing a consultant to undertake much of the work would be
the most efficient way to proceed. However, we have also concluded
that the process will take something in the order of six months and
costs tens of thousands of dollars. With these resource issues in
mind, we are wandering as to the worth of the final product.



In spite of the time and money spent on pursuing this issue, the
final product will be little more than a number that, provided we
don't have any significant changes to any of the contributing
variables may give us a reliable risk metric. The concern is that
the process of estimating and validating the risk metric will
consume a reasonably large amount of time and resource, while
adding little or nothing to the safety of our operations. I can't
help thinking the time and resources could be better used on other
projects.



We have not yet made a clear decision about our final response to
the recommendation. However, we felt it was necessary to give you
an undertaking that we are actively considering it.

As you are aware, Recommendation R20040056 requested that
Airservices estimate the overall midair collision risk at the
General Aviation Aerodrome Procedures (GAAP) locations.

As stated in our interim response to the Recommendation, the
development of a mathematical model to estimate this risk would
need to encompass operations outside of the hours of coverage as
well as those when the GAAP towel is manned.

I would suggest that the solution to this would be the
development of defined minimum safety standards which, before they
are exceeded, initiate airspace change to mitigate risk.

As the service provider we would like to suggest that the
development by CASA of the CASR Part 71 would establish a framework
of minimum standards.

We also wish to formally advise that the regulatory
responsibility for this recommendation resides with CASA as the
airspace regulator as of 1 July 2007. We are also happy to
participate in any discussions and provide assistance where
appropriate.

Civil Aviation Safety Authority (CASA) actions:

On 21 July 2009, following a number of reviews of General
Aviation Aerodrome Procedures (GAAP) aerodromes the Director of
Aviation Safety, CASA, issued a legal direction to Airservices
Australia to implement United States (US) style Class D procedures
at all GAAP aerodromes as well existing Class D aerodromes and
Avalon aerodrome effective 3 June 2010.

The Office of Airspace Regulation (OAR) conducted a Post
Implementation Review (PIR) (
http://www.casa.gov.au/wcmswr/_assets/main/lib100077/classd-postreview.pdf)
to evaluate the new Class D procedures at all new and existing
Class D aerodromes and determine the need for any additional
actions or improvements to these procedures.