In the previous thread:
alphacentauri
The GPWS tests I alluded to in the above post were after the incident.
Those flights, one in a Metro and one in a Conquest, were they properly conducted? The coroner didn't seem to think the first Metro flight was:
"In response to concerns the ATSB raised abut this possibility CASA commissioned Mr Bryant, an experienced pilot and aviation consultant, to conduct a test flight in a Metro aircraft equipped with GPWS to fly the runway twelve RNAV GNSS approach to Lockhart River using the advisory stabilised slope as published and additionally using the "step down" approach, flying not below minimum safe altitude at each step in the approach. Mr Bryant found that using the stabilised slope method of approach and with the aircraft configured appropriately, at normal speeds, no GPWS alerts were activated. There is however some doubt as to whether, when undertaking this test, the aircraft flew over the highest ground under the approach path.
Further, flying a stabilised approach at high speeds caused GPWS alerts to be activated. So too did the use of the step down approach where at 5.3 nautical miles to waypoint LHRWM, at 2,060 ft, a "terrain terrain" hard warning occurred and at 4.6 nautical miles to that waypoint a further "terrain terrain" hard warning occurred.
I was concerned that the letter sent by CASA to the ATSB advising of the results of its test flights was not as frank as one would expect communications between collaborating safety agencies to be. Neither of the reservations referred to above were mentioned. I was therefore relieved to hear that the agencies will undertake further examination of this issue to determine whether a problem in fact exists."
However CASA again didn't involve them in the second Conquest flight!
As K mentioned in an earlier thread, the Coroner had some serious reservations about the regulator vs investigator relationship:
“Finally, I wish to return to the concerns I expressed earlier about the working relationship between CASA and the ATSB. In this and previous inquests I have detected a degree of animosity that I consider inimical to a productive, collaborative focus on air safety. CASA’s submissions in this inquest suggest there was a danger of the ATSB’s recommendations being ignored and I continue to detect a defensive and less than fulsome response to some of them. I am aware that others in the aviation industry share these concerns, although I anticipate the CEO’s of the two agencies will disavow them.”
However the two flights conducted were somewhat irrelevant, as the ATSB engaged Honeywell to conduct a some what more 'scientific' approach and used an appropriate simulator with a GPWS, see Appendix F :
http://www.atsb.gov.au/media/3148359...appendices.pdf
Those findings showed that there would have been several 'hard warnings' from the GPWS for the aircraft's config!
These findings, however, were discounted by the regulator why?
alphacentauri:
The aircraft used to validate the original procedure was a Navajo, to the best of my knowledge it was not equipped with GPWS. There was and is still no requirement in the certification process to assess GPWS warnings, although it is brought to CASA's attention if one is found to alarm during a flight test. Further investigation usually results until the regulator is satisfied for publication.
This outdated attitude doesn't make it right though!
Because there wasn't a requirement to test GPWS on instrument approaches. There still is no requirement to do this, however the procedures are now flown using a GPWS fitted Conquest.
Which still didn't excuse not pulling the approach for four long years after the accident!
