Quote:
Originally Posted by Philip Argy
If air space is unmonitored, isn't the separation increased? If so, that will result in fewer aircraft concurrently occupying the unmonitored space which could make CASA's reported proposal simply a truism ...  |
Not quite as simple as that Philip.
Effectively there is no separation because there is no one to establish and monitor the separation between aircraft except the pilots. TIBA procedures basically instruct pilots to maintain a listening watch on a specific frequency and make broadcasts, presumably of position, altitude, time at that position and an ETA for the next position, at specific times/places.
Pilots then must work out for themselves if any aircraft that they have heard making a broadcast is a threat to their aircraft. With the further aid of TCAS pilots must work out what aircraft could come into conflict with them and what must be done to ensure there is separation with those aircraft.
In poor visibility/weather conditions or at night, with high closing speeds, possible ignorance of TIBA procedures (as has happened) and possibly one or more of the flight crews not having English as a primary language, working out some satisfactory separation is not assured. Throw an aircraft system problem/unseviceability, which is occupying the flight crew's attention, into the mix and the risk level increases. (The holes in the Swiss Cheese start lining up)
In my opinion it is a reasonably safe procedure if everything works as it should but the risk of a mid air is increased without ATC providing "positive separation".
I guess it comes down to each company/pilot making a risk assessment as to whether the risk is significant or acceptable. I wonder what the insurers of the aircraft are making of these procedures.
At the moment there is no restriction I am aware of that limits the number of aircraft in TIBA airspace.
I believe CASA is in the process of reviewing TIBA procedures and may instruct Airservices Australia (AsA)to declare controlled airspace (CTA), that is not being looked after by an ATC, as a TRA (Temporary Restricted Area). By doing that AsA will be able to issue individual permissions for aircraft to transit that airspace thereby limiting the number of aircraft in that airspace. This has happened before during the rare ATC strikes and was very restrictive in those cases.
As I see it, the only satisfactory answer, if traffic levels are to be maintained, is to have enough ATCs to ensure that all CTA is manned properly and that solution seems to be at least 12 months away. Even then AsA will have to stem the flow of Aussie ATCs resigning to take up better paid ATC positions overseas.
Regards
Stephen