Originally Posted by
Clinton McKenzie
And the biggest problem with your logic is that although ‘controlled airspace DOES NOT stop collisions’ (and nor do traffic lights), controlled airspace (and traffic lights) are more effective than nothing in preventing collisions. It’s a simple concept: In which airspace would you prefer your loved ones to be carried in the back of a 737: G or some other classification?
I could be wrong. It may be that we’d all be safer if all airspace were G.
There are benefits for safety in Class D, but our concept of CTA is no different to the 1950s, two way VHF with simplistic procedural based separation. There is still no more protection from errors or rogue aircraft in the non Radar class D environment than 50 years ago, so conflicts will continue to happen. Collisions in CTA have occurred at a regular rate throughout history, the major thing that has happened that has changed all that is the adoption of TCAS/ACAS. My argument is that class D will offer marginal safety benefit (eg PA-28 almost hit an ATR in Albury) for greatly increased cost and complexity. Where TCAS has proven itself over and over in successfully alerting and avoiding collisions. Mandating some form of TCAS/ACAS interpretative device be fitted to smaller craft as well as VHF radio would solve this very quickly.
By the way separation between VFR and IFR in class D is not provided by the tower, only traffic information. Positive separation is provided only between special VFR and IFR. So outside of tower visual contact, in VMC, IFR can still be passing VFR at close range even with clearances on the basis of see and avoid, which does not fix the problem at Ballina.