Hi Dick,
My conversations since leaving CASA lead me to understand that the reference to 1200 feet at Ayers Rock became a sticking point because neither CASA OAR nor Airservices understands how Class E is made to work in the US.
AusAlpa is quite correct when it refers to the US Class E transition airspace down to 700 AGL or ground level as being the key. They also mention that VFR in the US is defined by the airspace, not the altitude requirements still used in Australia. (Due to us not having to deal with Class E below 8500feet) so:
- For a VFR aircraft to be in the vicinity of an aerodrome with 700ft or ground level E, during poor visibility, requires a Special VFR clearance, this would not be issued by ATC if there was IFR traffic. If it is VMC then the CTAF procedures we currently use in Class G are still required
- If the IFR traffic goes around from the approach minimums, whether 700 ft for an airfield approach or whatever the ILS minimum is for E ground level, the aircraft remains in Class E airspace, so a re-entry clearance is not required. The pilot simply climbs via the published missed approach, which the controller keeps available until the aircraft reports on the ground.
- PS - when I first rated in ATC in 1972, when Rocky TWR went home, BN Sector 3 took the airspace down to 1500 feet AMSL. If the pilot reported IMC on descent we would issue a leave and re-enter CTA to the LSALT following the instrument approach (VOR/DME I think). Hence this form of operation has been used by Australian ATC in the past
A couple of other points jumped out at me about the Safety Case obtained under FOI which I have not seen:
- It should not be a "design and Implementation" safety case (SC) as such an SC would not be possible before consultations had taken place.
- SCs in Airservices normally follow the process Concept, Design, then Implementation; this SC should have been a Concept document. A Design SC then occurs when the details have been sorted out to ensure that the Design is acceptably safe; an Implementation SC comes last because it often involves processes, such as training and documentation, which can only be completed just prior to commissioning.
- My last comment about the SC refers to the concentration of non-equipped VFR aircraft at the Class E lower level, highlighted by AusAlpa and being the only item in my own feedback. The reason being that the risk of the proposed change causing a collision between VFR aircraft at 1500ft AGL, an altitude, by the way, a VFR pilot cannot determine while flying on QNH, would have to be classified in the SC as very high. This is the unacceptable category in risk management and should have stopped the proposal in its tracks.