Midair collision in Victoria

[JDNSW]

It seems from news reports that there has been a midair collision between two light twins at Mangalore airport. There were two on board each plane, and no survivors. Both are reported as training flights, one local, one from Tyabb.

Weather conditions are reported as heavy cloud.

[Tins]

It seems from news reports that there has been a midair collision between two light twins at Mangalore airport. There were two on board each plane, and no survivors. Both are reported as training flights, one local, one from Tyabb.

Weather conditions are reported as heavy cloud.

Oh dear. The plane from Tyabb would likely have come up through the Kilmore Gap. I'm not ascribing anything to anything, but the weather here recently makes that passage fraught. Read that again, I am not apportioning blame. Might be that conditions north of the Divide were clear, but Mangalore is close to Seymour, and many aircraft fall foul.

Midairs in the circuit?? Tragic.

[Hugh Jars]

We can thank the electronic dick for unalerted see and avoid separation.
There’s nothing more stressful than taking a 180 seat jet into a CTAF, and having to arrange your own separation with VFR traffic.

[Tins]

We can thank the electronic dick for unalerted see and avoid separation.

Guessing you know something we don't.



There’s nothing more stressful than taking a 180 seat jet into a CTAF, and having to arrange your own separation with VFR traffic.

180 seat jets don't usually use Mangalore... I'm struggling for reference here, Huge.

[JDNSW]

I think Hugh is talking about the influence of Dick Smith on changes to reporting rules at uncontrolled airfields.

Whether that had any relevance to this accident I don't know. My suspicion is that one or both of the aircraft were not actually in VFR.

[Hugh Jars]

Guessing you know something we don't.



180 seat jets don't usually use Mangalore... I'm struggling for reference here, Huge.

John, back in the 80's all aircraft on certain flight plans were given alerted traffic information by Flight Service (ie, full flight following). It was a valuable tool to enhance one's awareness of conflicting traffic. It was removed with reforms in the early 90's (from memory), and now (generally) only IFR aircraft are given traffic on each other. For the rest, it's unalerted see-and-avoid. There was a paper written in the 80's about the limitations of such separation practices, but the reforms were forced through anyway.

My reference to the Mangalore location is relevant. I fly into places like Ayers Rock, Ballina, Mildura, Hervey Bay, Kalgoorlie, Newman, etc in the jet. We get a limited traffic service at Ayers Rock and Ballina, but essentially all these places have similar operating procedures (CTAF) to Mangalore. That is "lookout, and don't hit anyone". In other words, arrange your own separation, aka unalerted see-and-avoid.

So, if both these aircraft were operating VFR, it's possible they did not know about each other, didn't see each other, and clearly unalerted see-and-avoid procedures did not work yesterday in the Mangalore area.

Unalerted see-and-avoid usually works in these places when people talk to each-other on the radio. A lot of the time there is traffic in these CTAFs, and we don't know about it because the other pilots are not broadcasting (or listening), or the frequency is jammed by aircraft operating at nearby airports. THAT can be a problem.

The slowest speed a passenger jet (like a B737) can fly in the landing pattern can be up to 3 times the speed of a light aircraft doing the same thing. So if I'm following a lighty that I can't see and don't know about, that is a real problem and a collision risk. If I know about the other traffic, I can modify my flight path to make it work (and be safe).

The above is an illustration of some of the complexities of operating into airports with CTAFs like Mangalore, Mildura etc.

[Hugh Jars]

Update:

It appears both aircraft were on IFR flight plans. That opens a whole 'nother can of worms. They should have been made aware of each other by ATC, and separated themselves.

[JDNSW]

Thanks for detailing it, and I was generally aware of it. I remember one occasion in the 1980s (I'd have to search my log book for the date) when I was flying from Dubbo to Lilydale, and diverted to Mangalore because of weather on and south of the ranges (fog). It turned out that all airports in Melbourne area were below IFR minimums as well, and by the time the fog started to lift about lunchtime, there was quite a collection there. No jets that I can remember, but there were a couple of F-27 RPTs (if I remember rightly, one was Canberra-Albury-Melbourne, the other Hobart-Melbourne) plus a large cargo plane, DC-6 I think, but might have been a DC-4. Plus a collection of light aircraft.

Quite an interesting discussion among the aircrew assembled in the old terminal building. A crisis was developing for the cargo plane - the crew was about to run out of hours for the day, but was averted when the news came through that Essendon was opening.

[4bee]

Just watched a You Tube for CTAF. Supposed to be genuine but how would you know? What a bloody nightmare with all & sundry calling in with utter bull****! Well, it was in the USA. One assumes Oz is not a lot better.

Onyer dick, you will be remembered for this cockup & I was sure you wanted to improve aviation standards here..[bigsad]

[JDNSW]

Update:

It appears both aircraft were on IFR flight plans. That opens a whole 'nother can of worms. They should have been made aware of each other by ATC, and separated themselves.

As you say, that opens a whole different can of worms. "Was it an ATC failure or a pilot failure?" How low does radar coverage go there do you know? Not very low I would think.

[JDNSW]

According to an ABC report, just published, they were at about 4,000ft. That is not in the circuit area, although it seems one was on the climb from Mangalore and the other descending to Mangalore. And it confirms both were IFR.

[Hugh Jars]

As you say, that opens a whole different can of worms. "Was it an ATC failure or a pilot failure?" How low does radar coverage go there do you know? Not very low I would think.
John,
I don't know what failed. We use a combination of radar and ADSB these days, so I assume there would be reasonable coverage in the area.

For the non-pilots, to understand how the system works today, one needs to understand how it worked before it was interfered with...

The previous system had FS (Flight Service), who were not Air Traffic Controllers. They operated the non-controlled airspace beneath controlled airspace. They provided flight following, traffic information (essential) for all aircraft on a flight plan, and coordinated clearances with ATC for those aircraft entering controlled airspace from below. They also manned the now defunct briefing offices around the country, where we used to do our flight planning. Places like Dubbo also provided a traffic information service at the aerodrome as well

They provided a valuable, and IMO, an essential service.

Air Traffic Control just looked after controlled airspace via its enroute, approach, departures and tower controllers. They provided positive separation, either by radar or by procedural means (in the absence of radar coverage). Procedural separation involves the use of time, distance and altitude restrictions between aircraft based on reports from the pilots, and mathematical calculations by the controller. Kind of like a 3D game of chess, which had to be very accurate. Procedural separation is still used today at Class D towered airports, such as Coffs, Mackay, Rockhampton, Tamworth etc.

The same procedural model was used by Flight Service for assessing potential traffic to pass on to pilots for their own separation purposes.

Fast forward to today: With the closure of Flight Service in the early 90's, pilots operating outside controlled airspace now get a significantly lower priority and level of service. This is now provided entirely by an otherwise busy ATC, who looks after the overlying controlled airspace.

The limit of service is between IFR and IFR traffic (remember the ATC is looking after overlying airspace, too). VFR aircraft generally don't receive a service, and without ADSB/radar or actually speaking with ATC, ATC won't even know the VFR aircraft is there, so how can they provide a service?.

Theoretically, with thecurrent system, if both yesterday's aircraft were IFR, they should have received (at the very least) a traffic advisory service from ATC using discrete transponder codes. If there is ADSB/radar coverage in the area, ATC could tell them exactly where the other aircraft was. Nevertheless, both aircraft would have known about the other.

If one aircraft was VFR (and squawking code 2000), ATC would tell the IFR aircraft of "an unidentified VFR paint 3 miles north of Mangalore at 4000 feet unverified" (or similar). This is workload permitting for ATC (I think).

If both aircraft were VFR, ATC will only provide a service on request, and only if their workload is permitting. Remember, they are controlling aircraft in the airspace above.

In all of this, even if ATC provided a traffic information service to these guys yesterday, it's still up to the pilots to talk to each other and coordinate their own separation procedurally. If there was an imminent conflict, ATC would usually alert the pilots that they were at risk of collision, but the pilots would still need to take their own evasive action. We don't know about this aspect, yet.

Notwithstanding all the above, The pilots should have been talking to each other either on the CTAF, on the area frequency, or both to arrange their separation. We don't know (yet) whether they were. This is where the airspace limitations and human factors come into effect. Limitations of the system? There are many. Combined nearby airports on the same CTAF frequency, which are often jammed by aircraft operating many miles away, preventing timely broadcasts (the old analogy of 'can't get a word in edgeways'). To monitor both area and CTAF, you need 2 radios. Did they both have 2 radios? Was the ATC overloaded looking after all that airspace? These are but a few limitations.

Human factors is more complex, and a can of worms. Operating into a busy CTAF is one of the highest risk operations you can do. I'm not afraid to say I hate operating the jet into them. You typically have a lot of relatively inexperienced pilots operating there. Toss in a busy flying school or two, and it's even tougher. A lot of students who have very little experience dealing with large numbers of aircraft (it's not their fault). Developing a mental model of the traffic situation requires skill and experience that students may not have. There are many other scenarios that I won't bore you with...

I understand both flights were advanced training flights with highly experienced pilots onboard. That's a particularly difficult situation to be in - delivering your lesson effectively and maintaining an effective traffic picture in your head. I did that for many years, and it's as challenging (but in a different way) as taking the jet or high performance turboprop in.

I'll be interested to hear the outcome. I'm not surprised it happened. It's almost happened countless times before under the "new" system. It was only a matter of time, sadly...

[JDNSW]

Just watched a You Tube for CTAF. Supposed to be genuine but how would you know? What a bloody nightmare with all & sundry calling in with utter bull****! Well, it was in the USA. One assumes Oz is not a lot better.

Onyer dick, you will be remembered for this cockup & I was sure you wanted to improve aviation standards here..[bigsad]

I have flown myself in the USA, and can confirm that radio is (or was) vastly more disciplined here than there.

[4bee]

That is a real consolation, John. What a bunch of Bushrangers/Desperadoes that lot are!