The ATSB report
From my initial reading of the ATSB report, it appears to be a well-balanced and objective statement and analysis of the facts. It obviously avoids emotive or political comments.
Some contributors have mentioned the fact that the ATSB report states:
In this occurrence, all aircraft were in Class E airspace and there was no prescribed separation standard applicable, therefore there was no infringement of separation standards.
The circumstances of this occurrence did not constitute an airprox occurrence.
We can (and no doubt will) debate the issue of whether or not this is desirable, safe or efficient, but the ATSB report seems to simply be stating a fact: No separation is required – therefore no separation breakdown can occur. (Even if they collide, as has been pointed out before)
I found it interesting to note the following comment in the ATSB report:
It would have been difficult for the pilot of the C421 to assume responsibility for separation with the 737 while being radar vectored by ATC.
Firstly, I believe that the phrase ‘assume responsibility for separation’ is misleading, as it implies that there was a time when the C421 was
not responsible for separation (i.e. see and avoid). What it does highlight is that the C421 was
unable to see and therefore avoid the B737 – but this is distinct from having the responsibility to do so.
Secondly, there appears to be an implication that an aircraft, whilst being vectored, might be in a position where it is unable to see and avoid other traffic. I question the effect this has on areas where the majority of
IFR aircraft are either on vectors or some other form of active control input to separate from
other IFR traffic.
Does this mean that, while I am vectoring an aircraft for whatever reason, I am compromising the pilot’s ability to see and avoid the traffic I may not know about?
Also, what does it do for the concept of ‘separation assurance’ which is being so strongly pushed by CASA and Airservices? For example, what happens when a vertical requirement I issue for separation is in conflict with the IFR pilot’s need to self-separate form a VFR aircraft. (This could happen in non-radar airspace for instance, where I cannot know about the VFR)
An observation
I have done an informal survey of Mode C readouts on my ASD over the last few days, to determine the efficacy of the hemispherical rule in reducing conflicts.
The results (very rough figures):
Of known IFR flights, more than 98% indicate Mode C at exactly the right level. The exceptions appear to be BA46 aircraft, which ocvcasionaly have Mode C readouts 100FT higher then the cleared/reported levels.
Of the VFR flights which appear to be in level flight, approximately 30% are at exact VFR levels. Approximately 60% are at levels between 100 and 300FT from the appropriate hemispherical cruising level. The remainder are a mixture of:
a) Exactly at an IFR cruising level
b) Exactly at the incorrect VFR level (non-hemispherical)
c) Within 100 to 300FT of the incorrect VFR level
For some reason, 6,800Ft seems to be the most 'popular' level.
The reason I mention this is that accurate level-keeping in cruise (including cruising at the correct level) is an important safety factor in any ‘uncontrolled’ situation. It applies equally to Class G and VFR in Class E.
It is important that pilots are aware of the need to ensure accuracy to avoid unpleasant surprises, whilst bearing in mind that during climb and descent (either yours or the other aircraft), see and avoid might be the
only collision avoidance system. So, keep one eye on the altimeter, one eye out of the window, one eye on the chart and the other eye on the aircraft.