ASD-B IN – A different perspective on the recent hype

[Clinton McKenzie]

My attention was recently drawn to a rather curious post by the ATSB on LinkedIn, about the ASD-B rebate. The post says:We’re joining with the Australian Maritime Safety Authority in encouraging general and recreational aircraft owners to take advantage of the government’s Automatic Dependent Surveillance Broadcast (ADS-B) rebate program before it closes on 31 May next year.

To incentivise voluntary uptake of ADS-B installations in Australian–registered aircraft operating under Visual Flight Rules (VFR), the government is providing a 50 per cent rebate on the purchase cost – capped to $5,000 – of eligible devices and, where applicable, the installation. While eligibility rests on equipment providing an ADS-B OUT capability, devices that provide ADS-B IN, as well as low-cost portable ADS-B devices, are also eligible for the grant.

Hear from a NSW aero club who recently installed ADS-B thanks to the grant, learn how AMSA can use ADS-B data to better affect a rescue during a search, and how we can use ADS-B in our investigations to ultimately improve aviation safety by reading this [linked article].The linked article includes these statements attributed to Angus Mitchell, the ATSB’s Chief Commissioner: “The need for improved situational awareness for pilots was evident during our investigation into the mid-air collision of two IFR training aircraft near Mangalore Airport in 2020. While both aircraft involved in the collision were operating under instrument flight rules (IFR) and equipped with ADS-B OUT, neither aircraft were equipped with ADS-B IN systems, and nor were they required to be.”

To support its investigation into the mid-air collision, the ATSB initiated an aircraft performance and cockpit visibility study to determine when each aircraft may have been visible to the pilots of the other aircraft. The study has clearly showed that had the aircraft been equipped with ADS-B IN, the pilots would have been assisted in locating the other aircraft and alerted to its position much earlier than by visual acquisition.

“Both a cockpit display of traffic information with an ADS-B traffic alerting system or an electronic conspicuity device connected to an electronic flight bag application could have provided this advance warning of a potential collision to the pilots of both aircraft with this tragic accident probably being avoided,” Mr Mitchell said.I too urge everyone to take advantage of the rebate. But let’s get some perspective on what’s happening here.

The aim of the ADS-B rebate for VFR aircraft is not – or at least it was not originally - to improve the situational awareness and safety of VFR pilots, though that may coincidentally be an outcome in some limited circumstances. Nor is the aim of the rebate to make ATSB’s and AMSA’s jobs easier, though that may also be a coincidental outcome.

The primary aim of the rebate was – and so far as I can tell, remains - to make VFR aircraft more conspicuous – electronically – to IFR aircraft and the air navigation services system, so as to reduce the risks to IFR aircraft. Now the focus appears to have shifted to ADS-B IN and its claimed safety benefits for both IFR and VFR aircraft, even though ADS-B IN was not originally mandated for IFR aircraft.

I suggest that the shift in focus is in substantial part due to intractable inadequacies in air navigation services and airspace arrangements. Hopefully the ATSB is keeping an expert eye on those issues?

I also suggest that the ATSB should be a little more circumspect in extolling the benefits of ADS-B IN, particularly for VFR aircraft. There are many ‘ifs’ in a sentence that can logically conclude with ATSB’s statement that ADS-B IN: “greatly improves a pilot’s situational awareness and enhances the safety of their flight.”

Those ‘ifs’ include: If the pilot knows what the specific ADS-B IN system being used can do; If the pilot knows how to get the system to do that; If the pilot knows the failure modes of the system; If the pilot knows how to and does confirm the system is actually doing what the pilot assumes and hopes it’s doing and, most importantly: If the pilot always bears in mind than an absence of ADS-B IN returns (and radio silence) is no guarantee of the absence of other aircraft in the vicinity.

These extracts from an NTSB recommendation dated 13 May 2022 neatly summarise the intersecting limitations of see-and-avoid and ADS-B systems, while highlighting that even the ‘biggest and best’ ADS-B IN systems with traffic information displays and visual and aural conflict alert capabilities are not a situational awareness panacea, especially when the systems are not doing what pilots incorrectly assume they are doing:The National Transportation Safety Board’s (NTSB’s) final report on a fatal May 13, 2019, midair collision between a de Havilland DHC-2 Beaver and a de Havilland DHC-3 Otter near Ketchikan, Alaska, which occurred at 1221 local time in visual meteorological conditions, has highlighted once again the limitations of see-and-avoid. An analysis of the visibility of each airplane from the cockpit of the other indicated that the Otter was obscured from the Beaver pilot by the Beaver’s cockpit structure, right wing, and the passenger in the right front seat. Similarly, the Beaver was intermittently obscured from the Otter pilot’s field of view by a window post, most critically during the last 11 seconds before the collision. [Six deaths and nine serious injuries ensued.]

Over the last 2 decades, automatic dependent surveillance-broadcast (ADS-B)-supported collision avoidance technologies featuring displays of traffic and aural and visual alerting features have become widely available and increasingly affordable in the United States. Such technologies, if widely adopted, could substantially reduce the occurrence of midair collisions like this one. Surprisingly, the pilots of both aircraft involved in the Ketchikan accident had ADS-B-supported cockpit displays of traffic information (CDTI) available to them, but the systems installed in each airplane had certain limitations, and they were not effectively utilized. The ADS-B system on the Otter was not broadcasting pressure altitude information because an ADS- B control head that relayed pressure altitude information to the ADS-B transceiver was not switched on. The NTSB’s investigation determined that this device was turned off during a maintenance inspection performed 2 weeks earlier on the Otter, and its deactivation was not noticed by three different pilots (including the accident pilot) who subsequently operated the airplane. Pilots did not normally manipulate the ADS-B control head, and it was not listed on company checklists for the airplane. As a result, information about the Otter’s pressure altitude was not transmitted to the Beaver’s ADS-B system.

The Beaver’s ADS-B system supplied traffic information to a ForeFlight mobile application that could provide a CDTI on the Beaver pilot’s Apple iPad. The version of ForeFlight on the iPad had the ability to produce both visual and aural alerts but required the altitude of relevant traffic targets to do so. Because the Otter was not broadcasting pressure altitude and though it was transmitting GPS-based altitude, the transceiver on the Beaver was configured to only transmit pressure altitude, not geometric altitude, to the iPad. As a result, the ForeFlight application on the Beaver did not have altitude information about the Otter and so would not have identified the Otter as a collision threat or produced an alert as the airplanes converged. Additionally, if the Beaver’s ForeFlight “Hide Distant Traffic” option had been enabled, the Otter would not have been displayed at all (the lack of altitude data for the Otter would have resulted in the ForeFlight application treating it as a “distant” target). Simulations performed by the NTSB indicated that, if the Otter had been broadcasting pressure altitude, the ForeFlight application could have generated aural and visual alerts concerning the Otter 1 minute 44 seconds before the collision.

The Otter was equipped with a Chelton electronic flight instrumentation system that provided a CDTI on a display mounted on the instrument panel. The Chelton system was designed to produce aural and visual traffic alerts but, to do so, required that the relevant traffic messages it received from the transceiver (a FreeFlight RANGR 978) be in “alert status.” Although the Otter was originally equipped with a transceiver that could place targets in “alert status,” in 2015, the transceiver was replaced with a newer model that did not have, and was not required to have, such an algorithm. After this change, the alerting features available on the CDTI could not be activated. Therefore, although the Beaver was displayed on the CDTI, the Otter pilot did not receive any visual or aural alerts concerning the Beaver as the airplanes converged. Simulations performed by the NTSB indicated that a CDTI with alerting capability might have generated an alert concerning the Beaver 37 seconds before the collision.

According to the Otter pilot, the last time he looked at the CDTI was about 4 minutes before the accident. At that time, he saw “two groups of blue triangles,” or aircraft targets, several miles away; but his experience with common patterns of flight operations in the local area led him to believe that the targets would not intercept his intended flightpath. If the Otter pilot had subsequently been alerted to the approaching Beaver, he would likely have looked for the Beaver and maneuvered to avoid it.

The NTSB determined that the probable cause of this accident was the inherent limitations of the see-and-avoid concept, which prevented the two pilots from seeing the other airplane before the collision, and the absence of visual and aural alerts from both airplanes’ traffic display systems, while operating in a geographic area with a high concentration of air tour activity. Contributing to the accident were (1) the Federal Aviation Administration’s (FAA’s) provision of new transceivers that lacked alerting capability to Capstone Program operators without adequately mitigating the increased risk associated with the consequent loss of the previously available alerting capability and (2) the absence of a requirement for airborne traffic advisory systems with aural alerting among operators who carry passengers for hire.

This accident highlights how CDTI with traffic alerting can help pilots to overcome the limitations of the see-and-avoid concept and can mitigate the risk of midair collisions. As demonstrated in this accident, the presence of a CDTI in the cockpit does not by itself guarantee the effectiveness of the technology.

Pilots must be familiar with ADS-B equipment installed in their aircraft and ensure that it is always fully operational in flight. Pilots should know whether their equipment includes a conflict-alerting feature and, if so, what types of alerts will be given under different scenarios. Because of the variety of CDTIs available and the different capabilities of these systems, pilots might not be aware of the aural or visual information their system can provide. Understanding the potential differences between CDTIs is particularly important for pilots who fly multiple aircraft with different systems. If a CDTI with aural and visual alerting is not installed, one should be installed and consistently used. Pilots must continue to visually scan outside for conflicting traffic in visual flight rules conditions, but the circumstances of this accident underscore the importance of combining an effective visual scan with CDTIs and alerting in the cockpit.We’re all aware of the limitations of ‘see and avoid’. But the mitigation for those limitations at least so far as VFR pilots are concerned is not to stare at the screen of a gizmo in the cockpit displaying ADS-B IN symbols, trying to work out what they mean. Most of the ADS returns displayed on my EFB come from aircraft in the flight levels and are, particularly when flying anywhere in the ‘J curve’, a distraction from the real job of a VFR pilot.

It is true that ADS-B and other systems enable Centre to alert aircraft even in G airspace - whether VFR or IFR - that they are in potential conflict. I hear it quite often on the Area frequency and am thankful that it happens. But it’s also true that Centre is only doing that for VFR on a ‘workload permitting’ basis and sometimes the workload does not permit the provision of that ‘nice-to-have’ service. Radio silence from Centre is therefore not conclusive of an absence of potentially conflicting traffic.

Just look at the Ballina SFIS - not a ‘nice-to-have’ but a ‘supposed-to-be-delivered’ service due to the traffic density and consequent collision risks in the area - to see what happens when the air navigation service provider has higher priorities. The SFIS is simply NOTAMed ‘no-can-do’. But the traffic density and consequent collision risks don’t go away. Perhaps the airspace classification and dimension arrangements in the Ballina area remain a substantial part of the safety problem, ATSB?

And then there’s the Mangalore tragedy in which the air navigation service provider’s equipment reliably and accurately tracked and displayed two ADS-B equipped IFR aircraft in G airspace to the point of their mid-air collision and four fatalities, generating four Short Term Conflict Alerts for ATC along the way to the collision. That was after the ADS-B mandate for IFR aircraft was justified on the basis that it would help prevent precisely what happened. This from the ATSB report on the tragedy:When each of the STCAs displayed, the controller assessed the integrity of the alert in accordance with the [National ATS procedures manual] procedure. The controller reported checking the path of each aircraft using the set velocity vectors, the vertical separation of the aircraft, and confirming that traffic information about each aircraft had been passed to the other aircraft. Having assessed that the aircraft would pass each other and:

- the STCA was designed as an alert for a breakdown in separation standards

- there was no set separation standard in non-controlled airspace

- the pilots were responsible for their own separation

they decided that a safety alert or traffic avoidance advice was not required, and cleared the aural alert.The equipment on the two IFR aircraft generated what the air navigation service system construed as “nuisance” alerts – “an alert which is correctly generated according to the defined STCA system parameters (rule set), but is considered operationally inappropriate by the controller” - discussed further in the ATSB report. Many people were – and remain – astonished and appalled at that outcome.

Many of those alerts would not be construed as “nuisances” and dismissed as such if they occurred in airspace with separation standards. But changing the airspace arrangements around places like Mangalore and Ballina and… would create “nuisances” of a different kind: The airspace regulator would have to make those changes and the air navigation service provider have to employ more controllers.

Problem: What to do to shift the focus away from inadequate air navigation services and airspace arrangements, so as not to upset that status quo, while doing something that seems to address the risk of another IFR/IFR mid-air collision?

Solution: Encourage everyone to get ADS-B IN.

That way, Airservices is under less pressure to provide better or more services, ATSB continues to get all the data to help explain, in three dimensional graphic detail, the track to the smoking hole and AMSA continues to get all the data to better “affect” - I think the correct word in the context of ATSB’s statement is “effect” - a rescue if anyone survives. Meanwhile, the aviation safety and airspace regulator – CASA keeps its lips pursed and avoids eye contact. A new cockpit gizmo, subsidised by someone else, is an excellent solution for all the agencies concerned. Pats on the back all round!

VFR pilots should make no mistake: Our biggest risk - aside from inadvertent entry into IMC or fuel exhaustion or starvation - arises from being ‘heads down’ in the cockpit rather than keeping a proper lookout. There are of course visibility limitations created by airframe structures of every aircraft and the relative locations of other aircraft in flight. But it’s certain a pilot’s not going to see anything anywhere outside the aircraft while ever the pilot’s focusing on a gizmo in the cockpit and making the assumption it’s a source of traffic truth.

Assumptions about the absence of conflicting returns on a ADS-B IN system display and silence on the radio can lead to a dangerous false sense of safety. Just as there are plenty of explanations for silence on the radio, only one of which is the absence of other aircraft in the vicinity, there are plenty of explanations for no ADS-B IN system returns, or inaccurate information, on an ADS-B IN display. (Most of the traffic based at my local aerodrome involves aircraft that have no ADS or SSR transponder - at least none that’s switched on - whose pilots are best described as ‘taciturn’.)

There are plenty of examples of VFR pilots seeing an ADS-B IN return on their EFB and using that information to see and avoid - or mutually arrange separation from - another aircraft. And there are plenty of examples of IFR aircraft seeing VFR ADS information and doing the same. And that’s a great outcome. But those pilots don’t know what traffic wasn’t displayed accurately or at all in their cockpits at the time. There is no guarantee that all traffic in the vicinity will ever be displayed by ADS-B IN systems. And as with any other aircraft system, you have to know what the specific ADS-B IN system you’re using can do, how to get it to do what it can do and how to confirm it's actually doing what you assume and hope it’s doing, and that means understanding the system’s failure modes.

For all those reasons and more, I consider this to be an overstatement by ATSB:To support its investigation into the [Mangalore] mid-air collision, the ATSB initiated an aircraft performance and cockpit visibility study to determine when each aircraft may have been visible to the pilots of the other aircraft. The study clearly showed that had the aircraft been equipped with ADS-B IN, the pilots would have been assisted in locating the other aircraft and alerted to its position much earlier than by visual acquisition.There are lots of “ifs” missing from that sentence and the ATSB’s categorical “would have” conclusion. Both the Otter and Beaver in the Alaska tragedy were equipped with ADS-B IN but that didn’t result in either pilot comprehending the location of the other’s aircraft into which they collided.

The ATSB went on to say:Both a cockpit display of traffic information with an ADS-B traffic alerting system or an electronic conspicuity device connected to an electronic flight bag application could have provided this advance warning of a potential collision to the pilots of both aircraft with this tragic accident probably being avoided.Could have. If. Probably. The Beaver in the Alaska tragedy was carrying an EFB with a traffic alerting system. It didn’t work in the case of the Otter because the Otter was, unknown to its pilot and previous pilots, not broadcasting pressure altitude information. The Otter had traffic alerting capability, too. Until it was removed.

The equipment actually fitted to the Mangalore aircraft in compliance with regulatory requirements actually ‘triggered’ Short Term Conflict Alerts in the air navigation service system. Another description of those alerts is “advance warning of a potential collision”. That’s the very purpose of STCAs. And the pilots of the aircraft probably assumed – reasonably I would suggest, given all of the safety hype around the original ADS-B mandate – that the air navigation service system would pass on those warnings rather than being justified in unilaterally dismissing them. Perhaps the tragic accident would have also been avoided if IFR pilots had clearly understood what a dangerously invalid assumption they were making about what the new ADS-B system was going to do for them.

On the subject of cockpit gizmos, there is one which is very cheap, very reliable, very accurate and almost pilot-proof: A modern carbon monoxide detector.

I mention carbon monoxide detectors because of the NSW Coroner’s Court inquiry and findings in the wake of the tragedy in which seven lives were lost in the Beaver accident at Jerusalem Bay in Sydney in 2017. One of the useful (and disturbing) things a modern CO detector will show you is the high level of CO to which we’re often exposed while just taxiing around on the ground (or water) in ‘ordinary’, serviceable aircraft. It will also help you to work out what to do with vents and windows to reduce the levels of exposure. Many of you will be blissfully unaware of the extent of your on-ground exposure and CASA remains wilfully blind to it, relying instead on reports from LAMES about defects found during maintenance and waiting for more CO exposure-caused fatalities and injuries.

In the course of the Coronial inquiry CASA was asked, in effect, how many more fatalities it would take before CO detectors would be mandated. According the Coroner, the CASA witness “frankly acknowledged”:To be honest I'd say it would take probably unfortunately a number of accidents, hopefully not fatal, to trigger the risk level to be in the range where regulatory action would be required.Translation: Affordable safety. CASA has decided that the value of lives potentially saved by mandating CO detection equipment is not sufficient to justify the mandate.

The evidence given by CASA was to the effect that there are approximately 8,365 single piston engine aircraft in operation in Australia and that dash-mounted CO detectors cost about $1,200. (Let’s set aside the fact that there are much cheaper options that are just as reliable and accurate, and include aural and visual alerts, as some panel mounted versions – remember how long it took to get rid of the fixed ELT mandate and how long it took for EFBs to be accepted by the regulator?) On CASA’s figures that’s about $10,000,000 to fit the single piston engine fleet. So, that means CASA reckons it’s not worthwhile spending $10,000,000 on CO detectors until the further body count makes it worthwhile.

In contrast, to justify CASA’s regulatory response in the wake of the Angel Flight tragedies involving a total of six fatalities (one near Nhill in 2011 the other near Mt Gambier in 2017), Dr Aleck of CASA said:Our objective here is not to specifically address what caused those two accidents; it's to address what kinds of things can cause incidents and accidents of this kind. We're being prospective. If we were to wait for sufficiently robust data to support an evidence-based decision for every individual decision we took in this space, we would have to wait for a dozen or more accidents to occur.When asked by the Angel Flight CEO as to why CASA had chosen to by-pass the usual protocols for regulatory change, the then CEO of CASA said:I have the power; because it’s easy.Why was CASA “prospective” rather than waiting for more accidents in the Angel Flight case, by-passing the usual regulatory change process, but is waiting for more fatalities and injuries in the case of CO detectors? Answer: The capricious consequences of politics. Pressure was put on CASA by the federal government to be seen to do something in the case of Angel Flight and, sadly for the next victims of CO exposure, the Beaver tragedy barely raised a federal government eyebrow in the direction of CO detectors. That’s probably because of the time it took to work out that CO exposure was a factor in the tragedy.

Get ADS-B IN by all means. But don’t believe all the hype. It’s not a panacea for situational awareness or the intractable inadequacies in air navigation services and airspace arrangements.

Yours in aviation safety.

[Squawk7700]

I’ve been harping on about this for a while now… ADSB OUT is next to useless without ADSB IN.

Unless you are in direct contact with ATC then you are back to see and avoid. (But as we’ve seen even if you ARE in contact with them, it may not help!)

IN gives you a fighting chance to see someone in advance.

The sooner everyone gets ADSB out, the better, even if it’s just a SkyEcho.

[Cloudee]

I know FR24 has its limitations but I use it as a situational awareness aid and it is effectively ADSB IN if you are in a mobile coverage area. It’s also displayed on Avplan (but not on OzRunways I believe). However, eyes out of the window is my best defence. Just a few hours ago a foreign student in an FTA Diamond made a very poor departure call while I was flying in the vicinity. It was visible on FR24 and that greatly assisted in spotting it visually.

[Squawk7700]

Cloudee, get yourself a Stratus box or a “Ping” ADSB-in device and you’ll see the traffic real-time from aircraft to aircraft, right there on your phone or EFB without the delays and latency of the 4G system.

Better still, if you can afford it and you are flying in different aircraft / not your own, try to stretch for a SkyEcho.

[Mr Mossberg]

Doesn't the rebate cover a SkyEcho device as well?

[Clinton McKenzie]

Doesn't the rebate cover a SkyEcho device as well?Yes.

I purchased and use one, the cost of half of which was rebated.

[PiperCameron]

Cloudee, get yourself a Stratus box or a “Ping” ADSB-in device and you’ll see the traffic real-time from aircraft to aircraft, right there on your phone or EFB without the delays and latency of the 4G system.

There is still no excuse for not keeping your eyes outside if you're flying by Visual Flight Rules.. The aircraft I fly are not fitted ADSB-out (yet) and one doesn't even have a transponder, so even FR24 only goes so far.

As the saying goes: It's the one you don't see that'll get ya. :}

[43Inches]

ADSB/ACAS/TCAS are all fallback devices, that is when the human fails to keep the picture the devices take over. I'm all for reasonable implementation of these things, however it should be very well understood that it does not replace the basics of situational awareness, lookout and monitoring the appropriate radio frequency. Some simple things that add to situational awareness; Listen to the Aerodrome frequency from quite a distance out, especially if you have two comms, you do not have to transmit, you are just listening for possible conflicts. Make informative, concise radio calls at the appropriate time, too early and new traffic won't hear you, too late and you already could be a conflict, anywhere near the circuit and approach paths (ie 5 mile final) is too late. Remember VHF is line of sight, if you are approaching an airport in hills, make another call when the airport is LOS, same on departing, make a departure call when at sufficient height so inbound aircraft can hear your departure track. Make calls BEFORE you do something, making an entering x runway as you are already entering defeats the purpose, you have already pulled out in front of possible traffic, you have not given other traffic the chance to announce a conflict. And of course don't let yourself get distracted when approaching an aerodrome, make sure there's no big checklists, passengers moving around, ask them to keep the chatter down if it's taking up your head space so you can concentrate on the approach, landing and any traffic. And of course be predictable, don't get in the habit of rushing, or anything unusual like tight circuits, straight in approaches etc without clearly stating that on the radio. Being on a normal length predictable circuit not only helps promote stable approach, but also gives other traffic more time to sight you.

[Capn Bloggs]

Wise words, 43. :ok:

[Cloudee]

ADSB/And of course be predictable, don't get in the habit of rushing, or anything unusual like tight circuits, straight in approaches etc without clearly stating that on the radio. Being on a normal length predictable circuit not only helps promote stable approach, but also gives other traffic more time to sight you.
Wise words. Pay attention jump pilots and glider tug pilots.

[Clinton McKenzie]

Another advertisement from the ATSB about ADS-B IN (https://www.atsb.gov.au/media/news-items/2023/moorabbin-near-collision-further-highlights-importance-ads-b).

This time the advert has been triggered by a “near collision” between two VFR aircraft in the Moorabbin training area.

VFR aircraft.

In a Delta area.

The ATSB keeps dealing with this issue as if there are only ever ‘isolated pairs’ of aircraft. One Sling and one Piper Cherokee. One Seminole and one Travel Air.

If all the ‘ifs’ line up and there are just two aircraft in proximity, laterally, and the pilot of one or both aircraft ‘see’ and accurately interpret the traffic display of ADS-B IN at a glance down in the cockpit, great. But then there’s the common reality of busy airspace.


https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/640x537/ycwr_ysbk_502f60abba63a7228139d14dbd25aaa3a67e4a93.jpg
Which of the displayed aircraft, if any, is a collision risk to me on my track WAD - TWRN? (This is just a snapshot from the EFB provider supplied data, without my conspicuity device connected. Just assume they are ADS-B IN symbols in green.) You have the luxury of looking at a much bigger and stable display on your computer monitor.

(The latest ATSB advert includes a text box that says: “ATC Short Term Conflict Alert (STCA) between AEM and JQF.” Maybe Airservices should do in the Melbourne FIR what’s been done in the Brisbane FIR: Just turn off the SCTA functionality below 4,500’ so that ATC is not bothered by the nuisance.)

I finally note, again, that the Beaver and Otter in the Alaska tragedy were both fitted with ADS-B IN with all sorts of bells and whistles alerting capability … that wasn't functioning properly.

[PiperCameron]

Another advertisement from the ATSB about ADS-B IN (https://www.atsb.gov.au/media/news-items/2023/moorabbin-near-collision-further-highlights-importance-ads-b).

This time the advert has been triggered by a “near collision” between two VFR aircraft in the Moorabbin training area.

VFR aircraft.

In a Delta area.

The ATSB keeps dealing with this issue as if there are only ever ‘isolated pairs’ of aircraft. One Sling and one Piper Cherokee. One Seminole and one Travel Air.

As a regular visitor to the Moorabbin training area, I find the idea (as you rightly point out) that there might only be two aircraft in conflict at any one time frankly ridiculous. It's a "Danger" area for a reason!

The issue I have with ADSB-in (with or without all the bells and whistles) is the distraction it can cause visually looking for an aircraft that might or might not be in conflict (depending upon the actions of the other guy who, by definition is doing the same as you) whilst not seeing the aircraft without ADSB fitted at all!! As I've said before, it's the one you don't see that'll get you.

[421dog]

My attention was recently drawn to a rather curious post by the ATSB on LinkedIn, about the ASD-B rebate. The post says:The linked article includes these statements attributed to Angus Mitchell, the ATSB’s Chief Commissioner:I too urge everyone to take advantage of the rebate. But let’s get some perspective on what’s happening here.

The aim of the ADS-B rebate for VFR aircraft is not – or at least it was not originally - to improve the situational awareness and safety of VFR pilots, though that may coincidentally be an outcome in some limited circumstances. Nor is the aim of the rebate to make ATSB’s and AMSA’s jobs easier, though that may also be a coincidental outcome.

The primary aim of the rebate was – and so far as I can tell, remains - to make VFR aircraft more conspicuous – electronically – to IFR aircraft and the air navigation services system, so as to reduce the risks to IFR aircraft. Now the focus appears to have shifted to ADS-B IN and its claimed safety benefits for both IFR and VFR aircraft, even though ADS-B IN was not originally mandated for IFR aircraft.

I suggest that the shift in focus is in substantial part due to intractable inadequacies in air navigation services and airspace arrangements. Hopefully the ATSB is keeping an expert eye on those issues?

I also suggest that the ATSB should be a little more circumspect in extolling the benefits of ADS-B IN, particularly for VFR aircraft. There are many ‘ifs’ in a sentence that can logically conclude with ATSB’s statement that ADS-B IN: “greatly improves a pilot’s situational awareness and enhances the safety of their flight.”

Those ‘ifs’ include: If the pilot knows what the specific ADS-B IN system being used can do; If the pilot knows how to get the system to do that; If the pilot knows the failure modes of the system; If the pilot knows how to and does confirm the system is actually doing what the pilot assumes and hopes it’s doing and, most importantly: If the pilot always bears in mind than an absence of ADS-B IN returns (and radio silence) is no guarantee of the absence of other aircraft in the vicinity.

These extracts from an NTSB recommendation dated 13 May 2022 neatly summarise the intersecting limitations of see-and-avoid and ADS-B systems, while highlighting that even the ‘biggest and best’ ADS-B IN systems with traffic information displays and visual and aural conflict alert capabilities are not a situational awareness panacea, especially when the systems are not doing what pilots incorrectly assume they are doing:We’re all aware of the limitations of ‘see and avoid’. But the mitigation for those limitations at least so far as VFR pilots are concerned is not to stare at the screen of a gizmo in the cockpit displaying ADS-B IN symbols, trying to work out what they mean. Most of the ADS returns displayed on my EFB come from aircraft in the flight levels and are, particularly when flying anywhere in the ‘J curve’, a distraction from the real job of a VFR pilot.

It is true that ADS-B and other systems enable Centre to alert aircraft even in G airspace - whether VFR or IFR - that they are in potential conflict. I hear it quite often on the Area frequency and am thankful that it happens. But it’s also true that Centre is only doing that for VFR on a ‘workload permitting’ basis and sometimes the workload does not permit the provision of that ‘nice-to-have’ service. Radio silence from Centre is therefore not conclusive of an absence of potentially conflicting traffic.

Just look at the Ballina SFIS - not a ‘nice-to-have’ but a ‘supposed-to-be-delivered’ service due to the traffic density and consequent collision risks in the area - to see what happens when the air navigation service provider has higher priorities. The SFIS is simply NOTAMed ‘no-can-do’. But the traffic density and consequent collision risks don’t go away. Perhaps the airspace classification and dimension arrangements in the Ballina area remain a substantial part of the safety problem, ATSB?

And then there’s the Mangalore tragedy in which the air navigation service provider’s equipment reliably and accurately tracked and displayed two ADS-B equipped IFR aircraft in G airspace to the point of their mid-air collision and four fatalities, generating four Short Term Conflict Alerts for ATC along the way to the collision. That was after the ADS-B mandate for IFR aircraft was justified on the basis that it would help prevent precisely what happened. This from the ATSB report on the tragedy:The equipment on the two IFR aircraft generated what the air navigation service system construed as “nuisance” alerts – “an alert which is correctly generated according to the defined STCA system parameters (rule set), but is considered operationally inappropriate by the controller” - discussed further in the ATSB report. Many people were – and remain – astonished and appalled at that outcome.

Many of those alerts would not be construed as “nuisances” and dismissed as such if they occurred in airspace with separation standards. But changing the airspace arrangements around places like Mangalore and Ballina and… would create “nuisances” of a different kind: The airspace regulator would have to make those changes and the air navigation service provider have to employ more controllers.

Problem: What to do to shift the focus away from inadequate air navigation services and airspace arrangements, so as not to upset that status quo, while doing something that seems to address the risk of another IFR/IFR mid-air collision?

Solution: Encourage everyone to get ADS-B IN.

That way, Airservices is under less pressure to provide better or more services, ATSB continues to get all the data to help explain, in three dimensional graphic detail, the track to the smoking hole and AMSA continues to get all the data to better “affect” - I think the correct word in the context of ATSB’s statement is “effect” - a rescue if anyone survives. Meanwhile, the aviation safety and airspace regulator – CASA keeps its lips pursed and avoids eye contact. A new cockpit gizmo, subsidised by someone else, is an excellent solution for all the agencies concerned. Pats on the back all round!

VFR pilots should make no mistake: Our biggest risk - aside from inadvertent entry into IMC or fuel exhaustion or starvation - arises from being ‘heads down’ in the cockpit rather than keeping a proper lookout. There are of course visibility limitations created by airframe structures of every aircraft and the relative locations of other aircraft in flight. But it’s certain a pilot’s not going to see anything anywhere outside the aircraft while ever the pilot’s focusing on a gizmo in the cockpit and making the assumption it’s a source of traffic truth.

Assumptions about the absence of conflicting returns on a ADS-B IN system display and silence on the radio can lead to a dangerous false sense of safety. Just as there are plenty of explanations for silence on the radio, only one of which is the absence of other aircraft in the vicinity, there are plenty of explanations for no ADS-B IN system returns, or inaccurate information, on an ADS-B IN display. (Most of the traffic based at my local aerodrome involves aircraft that have no ADS or SSR transponder - at least none that’s switched on - whose pilots are best described as ‘taciturn’.)

There are plenty of examples of VFR pilots seeing an ADS-B IN return on their EFB and using that information to see and avoid - or mutually arrange separation from - another aircraft. And there are plenty of examples of IFR aircraft seeing VFR ADS information and doing the same. And that’s a great outcome. But those pilots don’t know what traffic wasn’t displayed accurately or at all in their cockpits at the time. There is no guarantee that all traffic in the vicinity will ever be displayed by ADS-B IN systems. And as with any other aircraft system, you have to know what the specific ADS-B IN system you’re using can do, how to get it to do what it can do and how to confirm it's actually doing what you assume and hope it’s doing, and that means understanding the system’s failure modes.

For all those reasons and more, I consider this to be an overstatement by ATSB:There are lots of “ifs” missing from that sentence and the ATSB’s categorical “would have” conclusion. Both the Otter and Beaver in the Alaska tragedy were equipped with ADS-B IN but that didn’t result in either pilot comprehending the location of the other’s aircraft into which they collided.

The ATSB went on to say:Could have. If. Probably. The Beaver in the Alaska tragedy was carrying an EFB with a traffic alerting system. It didn’t work in the case of the Otter because the Otter was, unknown to its pilot and previous pilots, not broadcasting pressure altitude information. The Otter had traffic alerting capability, too. Until it was removed.

The equipment actually fitted to the Mangalore aircraft in compliance with regulatory requirements actually ‘triggered’ Short Term Conflict Alerts in the air navigation service system. Another description of those alerts is “advance warning of a potential collision”. That’s the very purpose of STCAs. And the pilots of the aircraft probably assumed – reasonably I would suggest, given all of the safety hype around the original ADS-B mandate – that the air navigation service system would pass on those warnings rather than being justified in unilaterally dismissing them. Perhaps the tragic accident would have also been avoided if IFR pilots had clearly understood what a dangerously invalid assumption they were making about what the new ADS-B system was going to do for them.

On the subject of cockpit gizmos, there is one which is very cheap, very reliable, very accurate and almost pilot-proof: A modern carbon monoxide detector.

I mention carbon monoxide detectors because of the NSW Coroner’s Court inquiry and findings in the wake of the tragedy in which seven lives were lost in the Beaver accident at Jerusalem Bay in Sydney in 2017. One of the useful (and disturbing) things a modern CO detector will show you is the high level of CO to which we’re often exposed while just taxiing around on the ground (or water) in ‘ordinary’, serviceable aircraft. It will also help you to work out what to do with vents and windows to reduce the levels of exposure. Many of you will be blissfully unaware of the extent of your on-ground exposure and CASA remains wilfully blind to it, relying instead on reports from LAMES about defects found during maintenance and waiting for more CO exposure-caused fatalities and injuries.

In the course of the Coronial inquiry CASA was asked, in effect, how many more fatalities it would take before CO detectors would be mandated. According the Coroner, the CASA witness “frankly acknowledged”:Translation: Affordable safety. CASA has decided that the value of lives potentially saved by mandating CO detection equipment is not sufficient to justify the mandate.

The evidence given by CASA was to the effect that there are approximately 8,365 single piston engine aircraft in operation in Australia and that dash-mounted CO detectors cost about $1,200. (Let’s set aside the fact that there are much cheaper options that are just as reliable and accurate, and include aural and visual alerts, as some panel mounted versions – remember how long it took to get rid of the fixed ELT mandate and how long it took for EFBs to be accepted by the regulator?) On CASA’s figures that’s about $10,000,000 to fit the single piston engine fleet. So, that means CASA reckons it’s not worthwhile spending $10,000,000 on CO detectors until the further body count makes it worthwhile.

In contrast, to justify CASA’s regulatory response in the wake of the Angel Flight tragedies involving a total of six fatalities (one near Nhill in 2011 the other near Mt Gambier in 2017), Dr Aleck of CASA said:When asked by the Angel Flight CEO as to why CASA had chosen to by-pass the usual protocols for regulatory change, the then CEO of CASA said:Why was CASA “prospective” rather than waiting for more accidents in the Angel Flight case, by-passing the usual regulatory change process, but is waiting for more fatalities and injuries in the case of CO detectors? Answer: The capricious consequences of politics. Pressure was put on CASA by the federal government to be seen to do something in the case of Angel Flight and, sadly for the next victims of CO exposure, the Beaver tragedy barely raised a federal government eyebrow in the direction of CO detectors. That’s probably because of the time it took to work out that CO exposure was a factor in the tragedy.

Get ADS-B IN by all means. But don’t believe all the hype. It’s not a panacea for situational awareness or the intractable inadequacies in air navigation services and airspace arrangements.

Yours in aviation safety.


Just buy a Sentry. The top of the line model is less than 1/2 of the $1200 you quoted for a panel mounted CO detector, and it has a much better ADSB in and interface (as well as a recording g meter) than the couple of Stratii I’ve owned. Oh, and since Sentry pretty much invented home CO detectors, it’s the bomb among airborne CO alarms…

I put my sentry in other people’s aircraft when I’m flying with them (sticks to a window, does Bluetooth or Wifii. Likes to interface). and the number of burned out heater shrouds in singles (as well as two janitrol heaters which were within inspection dates, but had holes was amazing. Many of them had either chemical CO cards or actual electronic detectors, and none of them went positive below 150ppm

[Clinton McKenzie]

The $1,200 I quoted came from a CASA witness at the Beaver coronial inquiry, and was in AUD including installation. But that's just for a panel mounted CO detector without any ADS functionality. That’s an awfully expensive CO detector even taking exchange rates into consideration.

A highly accurate, 'pocket' CO detector with aural and visual alerts and Bluetooth capability costs around AUD300. That’s AUD2.5 million rather than AUD10,000,000 for the entire piston engine fleet in Australia (based on the fleet size used in CASA’s calculation). And if the mandate applied only to aircraft carrying fare-paying passengers, that brings the overall 'fleet cost' down even further. It appears to me that CASA does not put a very high price on a fare paying passenger’s life.

Your mention of equipment, like Sentry, with ADS-B IN functionality and traffic alert functionality and accurate CO detection and alert functionality points up another strange aspect of the ATSB’s current focus. Out of the Jerusalem Bay Beaver tragedy, ATSB recommended that CO detectors be mandated! That was rejected by CASA. I would have thought that if ATSB considers ADS-B IN and CO detectors to be such great enhancements to safety, ATSB would be extolling the virtues of the available ADS-B IN systems that include an accurate CO detector. (Does the Sentry WAAS GPS work here?)

(Those chemical CO cards change colour just after the pilot is sufficiently poisoned not to notice.)

[MechEngr]

"Which of the displayed aircraft, if any, is a collision risk to me on my track WAD - TWRN? (This is just a snapshot from the EFB provider supplied data, without my conspicuity device connected. Just assume they are ADS-B IN symbols in green.) You have the luxury of looking at a much bigger and stable display on your computer monitor."

Why isn't that interface also showing automobile traffic and Zillow prices?

It can project expected path but not filter for altitude? Sucky software sucks.

Per the mid-air followup, the alarms didn't go off because there was no pressure altitude to one ADSB-Out. Why was there no continuous alarm in that plane indicating a critical failure? Why no horizontal separation alert on either plane? Why not also use GPS geodetic altitude as well as pressure altitude? Sucky software and sucky specification sucks.

[Clinton McKenzie]

That's why the adverts from ATSB should include one of those really quickly read disclaimers at the end:

"Your ADS-B will be sucky unless...."

My version of that disclaimer is all of the 'ifs' I've explained earlier.

[Squawk7700]

​​​​In mid-October 2023, a Sling light sport aircraft and a Piper Cherokee operating in the Moorabbin training area, south-east of Melbourne came within 100 metres of each other while both aircraft were flying at the same altitude.​​​

That’s probably happened to me 20+ times over the years when transiting the Moorabbin training area, but I’ve never rang the alarm bell because it probably happens several times a day!

ADSB-IN won’t help all that much in the training area as there are too many turns being made and it’s almost impossible to tell which way the other aircraft is heading without staring at the ipad for 20+ seconds at a time.

I’m not a fan of the 4G ADSB-IN traffic because it’s too latent… you really need a SkyEcho or similar for the direct source of truth. In fact I might made a YouTube video to highlight the difference.

[MechEngr]

I suppose the problem is integrating flight-navigation software with situation awareness software. I expect the nav software guys add it because, for them, it's cheap and they don't care.

This looks as I would expect a traffic display to look:

http://www.nexairavionics.com/wp-content/uploads/Garmin-Pilot-App-ADS-B-Traffic-Display-.jpg

or

http://www.nexairavionics.com/wp-content/uploads/190-01004-04_G-58.jpg

[Squawk7700]

The little green lines are handy for predicting their direction, however the training area is so small and there are so many manoeuvres being made that you couldn’t keep track very easily.

Even if there were proximity alerts in your EFB with audible alarms, you wouldn’t know from direction the other aircraft was, because you may both be turning.

I know FLARM has a complex algorithm for this, however I wonder how the gliding guys deal with it… I guess they west a parachute for this reason ! (Amongst others)

[Clinton McKenzie]

Exactly, Squawk.

The ATSB has used a bad example in its recent advert. VFR aircraft in a published flying training Delta.

One need only watch what goes on (and to have been in there doing it) to know why ATSB should be very circumspect in plugging ADS-B IN as a useful tool for collision avoidance for VFR aircraft in training areas. If all you have is a screen in the cockpit displaying the 'raw' ADS aircraft symbols and data, you'll go crazy staring at that display trying to keep track of where everyone is now and going next. And if you have all the traffic alerting 'bells and whistles', they'll send you crazy too. (I now leave my CO detector off before take off, for analogous reasons. Once in the air I'll soon see whether the CO level is unusual.)

[43Inches]

Danger areas like the Moorabbin training area are marked for a reason, don't transit the area with your eyes closed and radio turned down, or avoid altogether. One thing that needs to be addressed is with all the new large flying colleges popping up CASA needs to mandate that they have prescribed training areas, away from main traffic paths and the dimensions identified on relevant maps as danger areas. Whilst the operators probably have training areas specified in their ops manuals no one else knows where these are unless marked on the map.

[missy]

Maybe Airservices should do in the Melbourne FIR what’s been done in the Brisbane FIR: Just turn off the SCTA functionality below 4,500’ so that ATC is not bothered by the nuisance.)
How does a ANS provider have different rules based on an arbitrary line on a map? Does this apply to the whole of the BN FIR?

[Clinton McKenzie]

The answer is obvious, missy: There must be profound safety consequences of crossing that line. I feel that 'chill' and the shudder in the airframe each time I cross.

For those who aren't across the facts underlying the comment I made and missy's question, this is from the ATSB report on the Mangalore tragedy:In the Australian ATC system STCAs occur in both controlled and non-controlled airspace, with alerts inhibited in some areas. Specifically, Airservices advised that STCAs in Class G airspace are inhibited below 4,500 ft in the Brisbane flight information region, but occur to the ground in areas of the Melbourne flight information region.The real answer to missy's question is the one of which I suspect missy is aware: Decades of, first, Airservices being left to its own devices as a consequence of the combination of CASA's inadequate regulation of the ANSP and airspace arrangements and, secondly, ATSB's inadequate investigations of the safety implications of the first.

[Clinton McKenzie]

Inbound to YMMB.

Ready…Setty…Stare!


https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1076x1226/img_1106_f34a3272ef32c6b1fda47838054bf432011afe4e.jpeg
Remember: You’ll be looking at a small display in a cockpit being rattled around by turbulence.

[Squawk7700]

I feel like Rainman looking at that pic and can see 3 or possibly 4 conflicts.

[Clinton McKenzie]

Well done! All you need to do is keep staring at that screen and your situational awareness task is done. The completeness and accuracy of the displayed traffic data is guaranteed! :ok:

[ER_BN]

Clinton,

Thanks for the inbound YMMB graphic, I've passed it onto someone far more qualified to comment than me, but the display and the associated irony of the MNG tragedy is noted.

RE: The MNG accident, seeing the ATSB investigation was just bumptious hubris and incompetence does anyone know when the coroner's inquiry is?

You mentioned 4 STCAs, perhaps it was my failure in reading the report properly but I could only see two re JQF and AEM? The initial and a re-alert.

It would be my understanding that after the first STCA was acknowledged by the controller, the STCA acronym remained constantly in both the aircrafts' track labels on the Air Situation Display until collision.

At a time before the collision the STCA re-alerted (that does not invalidate the previous sentence) but the derelict ATSB investigation never explained the reactivation.

There are a huge number of shortcomings in the report and I can sympathise with many pilots and controllers who have mentioned the word "cover-up".

When confronted with CONSPIRACY or INCOMPTENCE, I am an incompetence person myself as I think we reached "peak human" long ago.

That doesn't mean self interest, greed or snouts in the trough haven't played a part in decision making in AsA, CASA or ATSB.

Given the Senate Estimates are just a joke, I have sent off info to the NACC, though given the state of the Australia and the reported number in the NACC inbox, no doubt it's a far queue.

At least Lead Balloon can smile given that by all their comments in the MNG reports and their associated simplistic distraction of ADSB-IN, ATSB by implication if not by statement has declared CLASS G is safer for VFRs than IFRs. I have to laugh when Australian controllers issue traffic "alerts" VFR to VFR in G. The phrase "Get your hand off it" comes to mind. Sort out your IFR to IFR first. More surveillance has led to laziness in the whole process.

I honestly believe without surveillance (Radar or ATSB) and with FIS still existing MNG would not have happened.

Where's FSO Griffo when you need him...What, in OAP luxury at Mar a Lago....Half his luck!!

Australia - Centre of Excellence only in Mediocrity.

[Clinton McKenzie]

Re STCA’s, I’ve revisited the ATSB Report on the Mangalore tragedy. It says, with my bolding added:In the time between JQF taking off and the collision, there were three STCA alerts generated.

…

On the basis of analysis conducted by an ATC subject matter expert and technical detail provided by Airservices, it was assessed that:

The first STCA, at 1122:42, was a nuisance alert generated by JQF conflicting with VFR traffic in the Mangalore circuit area.

A second STCA, at 1122:49, occurred as the controller passed traffic information to JQF (Figure 13). At that stage, indications were that the aircraft would pass abeam each other. The STCA was assessed by the controller but not cleared from the screen at this point.

The controller re-inspected the two aircraft at 1123:30 after JQF had turned towards the planned outbound track. The velocity vectors indicated that lateral displacement would be maintained, with JQF passing behind AEM in about one minute. At that time, the controller’s display showed AEM at 4,800 ft while JQF was at 3,400ft.

A final STCA alert occurred at 1123:51. The controller zoomed in to inspect the aircraft flight paths and altitudes again and acknowledged the STCA at 1124:09. The controller identified that JQF was going to pass across the track of AEM, but at that time, 11 seconds prior to the collision, indications on the controller’s display showed AEM at 4,500 ft and JQF at 4,000 ft, with 0.9 NM lateral separation between the aircraft.So I’ll correct my ‘4’ to ‘3’ (though I’m still digging to find the provenance of my original ‘4’).

Perhaps your ‘2’ comes from Figure 13, described as “Recreation of STCA display at 1122:49”, which shows only 2 STCA ‘boxes’?

Of course, a recreation of the circumstances at 1122:49 excludes the “final STCA” which “occurred at 1123:51”. It’s very hard for me to fathom the logic behind the ATSB’s decision not to include the closest STCA in time to the collision in the recreation of the STCA display. The ATSB went to the trouble of recreating the display showing the velocity vectors as not intersecting at the time of the 1122:49 STCA but decided not to recreate the display showing the velocity vectors at the time of the STCA immediately preceding the collision. Go figure.

Of course, all of this is OK for IFR aircraft because there is no separation standard in non-controlled airspace. Meanwhile, some VFR pilot has an attack of the vapours after seeing another aircraft in close proximity in a published flying training Delta, and the ATSB uses that as basis for another advert for ADS-B IN, which advert included a recreation of the STCA. Go figure.

[missy]

The real answer to missy's question is the one of which I suspect missy is aware
Nope, I'm not sure that I do, divergent procedures either sides of on arbitrary line on a map that arcs 50miles north of Sydney and across the continent. National standardisation? Oversight by CASA?Periodic investigations by ATSB?
Probably a corporate history somewhere, someone would know but I do wonder who the BN Centre manager was who authorised the change? Who was the Safety Manager at the time? Who was the ATC GM or Head ATC at the time? Wouldn't the controller Union ( Civil Air ) raise an objection?

[sunnySA]

Probably a corporate history somewhere, someone would know but I do wonder who the BN Centre manager was who authorised the change? Who was the Safety Manager at the time? Who was the ATC GM or Head ATC at the time? Wouldn't the controller Union ( Civil Air ) raise an objection?
Perhaps the real question is "how" rather than "who"?

[ER_BN]

Clinton,

Thanks for your prompt clarification.

The STCA system by its very nature works on conflict pairs and in my previous post I noted I was referring to those STCAs specifically regarding the JQF/AEM pair.

As far as I can tell that is what the ATSB report indicates so we are in agreement.

Not sure what you meant by Perhaps your ‘2’ comes from Figure 13, described as “Recreation of STCA display at 1122:49”, which shows only 2 STCA ‘boxes’?
For tracks under the jurisdiction of the controller, the yellow "box" around the track labels of the two relevant aircraft is part of the TAAATS Eurocat Human Interface (HMI) to highlight the two aircraft and is yet to be acknowledged by the controller. 1 STCA in the circumstances of the MNG accident correctly produces 2 "boxes".

No one should assume that any ATSB graphical "re-creation" accurately aligns with what the controller saw on the TAAATS Eurocat Human Machine Interface.

My feedback to controllers at the time was that the STCA HMI would be displayed from 1122:49 to collision.

On the assumption that this is correct, the ATSB never explains why the STCA system changed the STCA HMI on JQF and AEM's track labels from Acknowledged status back to Unacknowledged status at 1123:51.

It would have been one of the first things I would have determined as part of the technical investigation, and I have done more than one hundred of them.

I have no idea whether that is what really happened or was displayed to the controller. Problems with TAAATS Eurocat Replay! That's the rhinoceros in the room!

And we haven't yet mentioned the elephant or the hippopotamus in the room either!

All this could be viewed as farcical but four humans died...

Do you think a GA pilot organisation might ask when the Coroner's Inquiry is going to happen?

Or are we happy that the memory of the 4 pilots is tainted by an inaccurate and incomplete ATSB report?

If you want to talk, PM me and I will call.

Have a good one!

[PiperCameron]

Well done! All you need to do is keep staring at that screen and your situational awareness task is done. The completeness and accuracy of the displayed traffic data is guaranteed! :ok:

Exactly. You've just missed the non-ADSB equipped aircraft in the mix... me!!

It probably seems busy to those unfamiliar with YMMB airspace and unaware there are two parallel runways in operation, but all I see looking at that pic is a normal busy day at Moorabbin, with the CAE-Oxford Cessnas doing their usual 3-mile circuits and the queue building at Carrum. As far as conflicts go, I have no idea where UUD is going, but then it's an LTF Sling (probably student solo) and you'd want to hope the other guy inbound has him in sight. Situation Normal. :rolleyes:

Suffice to say, the YMMB Tower Controllers do an amazing job keeping the kiddies in line day-in day-out.

[Squawk7700]

That “queue building at Carrum” resulted in a mid-air not that many years ago!

[PiperCameron]

That “queue building at Carrum” resulted in a mid-air not that many years ago!

Considering it's an almost daily occurrence (usually late afternoon rush-hour as all of the instructors try to get their pupils back on the ground before last light) I'm personally quite surprised it doesn't happen more often. But it doesn't. Which one in particular were you thinking of?

There have been quite a few "attempted landings" on the top of other aircraft (typically Cessnas - perhaps being mistaken for the factory roofs on short final?) in the circuit also, although ATC are quick to spot that now and tell 'em to go around.

[43Inches]

Maybe somebody should ask how Moorabbin survived with three runways in operation and twice the traffic back in the 70s/80s. Must have been the early model ADSB and ACAS. There was also times with contra circuits in operation on 17 or 13 with crosswind operations on 22. Moorbbin movement rates have not changed much in the last 20 years, sitting around 250,000 movements a year average, so nothing is 'new' in this airspace.

[Squawk7700]

This one https://aviation-safety.net/wikibase/22596

[PiperCameron]

Maybe somebody should ask how Moorabbin survived with three runways in operation and twice the traffic back in the 70s/80s. ....

This one

That one occurred back in 2008 up near Brighton - not Carrum - involving an aircraft taking off mixing with one inbound, and I note it only took them 3 years to prepare the final report: that's quick time for the ATSB! https://www.atsb.gov.au/publications/investigation_reports/2008/aair/ao-2008-059

According to the report, following this incident they subsequently (a) changed YMMB to Class D (b) placed restrictions on the number of aircraft in the circuit and (c) now insist that all arriving aircraft do so via specific VFR waypoints, including at Brighton (North) and Carrum (South) so.. nope, not relevant to this discussion I'm afraid. Water under the bridge and all that. :8

Maybe we're just lucky?!? But I have to believe it's more than that.

[43Inches]

That was in the circuit/north west of Moorabbin, not near Carrum. VH-CGT was inbound from the northwest, Brighton direction, and VH-UPY was doing solo circuits on the western circuit for some reason, and not very consistent circuits at that.

It interesting that GAAP airports came about due to concerns over high density operation of light aircraft, so after a study process including overseas experience they implemented GAAP. Which for 30 years or so was absolutely fine and then suddenly was not when an aircraft that should have been on the Eastern circuit doing solo circuits was caught out in an unfortunate situation. The problem now is that Class D can't handle the numbers (suprise, suprise) and they are looking for solutions that were already in place 20 years ago.

Moorabbin Airport had it's peak in movements in 1989 at 399,000 movements, 150,000 movements more that the last few years average, what has gone wrong?

One of the main concerns was radio traffic for control services, so a main concept in GAAP was to reduce radio traffic by not requiring full clearances and the traffic just followed each other with joining 'instructions'. The only clearance required was the take-off and landing part.

The waffle that has crept into ATC procedures lately really has significant safety implications in complex, busy situations.

[Squawk7700]

Cheltenham actually, but close enough.

[missy]

Inbound to YMMB.

Ready…Setty…Stare!


https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1076x1226/img_1106_f34a3272ef32c6b1fda47838054bf432011afe4e.jpeg
Remember: You’ll be looking at a small display in a cockpit being rattled around by turbulence.
Not to mention, sun glare, refections, dirty screen.

[Capn Bloggs]

One of the main concerns was radio traffic for control services, so a main concept in GAAP was to reduce radio traffic by not requiring full clearances and the traffic just followed each other with joining 'instructions'. The only clearance required was the take-off and landing part.

The waffle that has crept into ATC procedures lately really has significant safety implications in complex, busy situations.
Wash your mouth out with soap, 43. Australia-unique concepts/procedures cannot be allowed and ICAO Class D procedures WILL be implemented!! HWMBO said so!

Now back to normal programming. :}

If ADSB-In could be verified as accurate, then it would make the big boy's lives easier out in the sticks when dealing with bug smashers and frighteners.

[Mr Mossberg]

Class D was implemented to calm down (read, shut up) a prominent aviation identity. Except it isn't really Class D is it. Class D you can call inbound from anywhere, what we really have is GAAP re-named Class D. Carrum and Braahton were the only inbound reporting points I could find without putting it into the pad or GPS, meaning, you could find Carrum while still looking out the window instead of having to navigate via GPS via the other points cos they've all blended in to the urban sprawl. By the looks of that pic, most of them are going to head in via Carrum.

[ER_BN]

Extrapolating ATSB's "concept"...to reality.

Were the helicopters fitted with ADS-IN?

Surely that crash showed the "limitations of see and avoid" as per ATSB?

[Squawk7700]

By the looks of that pic, most of them are going to head in via Carrum.

The GMH building is another one. I saw a photo of it the other day on Facebook from back in the day. It was seemingly the only large building for kilometres. Now it’s completely lost in a sea of factories. I haven’t personally used that approach point for years as it heads to the busier circuit, is further to taxi, it backs more onto the training area and it’s entirely over suburbia. So as you say, Carrum is the preferred as it doesn’t have all that, plus it has beach to land on.

[43Inches]

Surely that crash showed the "limitations of see and avoid" as per ATSB?

If you are referring to the Moorabbin mid-air collision, CGT did see UPY and was taking avoiding action when they collided. My issue is why a solo student was using the Western Circuit, in days gone the Eastern circuit was used for solos as it had less inbound/outbound/crossing traffic, and the tower always had the ability to bring aircraft inbound via GMH and Academy for an overhead join to the Western circuit if the Eastern circuit was busy. The tower also has a better view of the Eastern circuit for traffic management.

The GMH building is another one. I saw a photo of it the other day on Facebook from back in the day. It was seemingly the only large building for kilometres. Now it’s completely lost in a sea of factories. I haven’t personally used that approach point for years as it heads to the busier circuit, is further to taxi, it backs more onto the training area and it’s entirely over suburbia. So as you say, Carrum is the preferred as it doesn’t have all that, plus it has beach to land on.

GMH as the name suggested was part of the General Motors Holden production facilities, sold in 1997. There were significant, stand out, saw tooth factory buildings, in isolation surrounded by a lot of parked vehicles.

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/1600x1551/1970_2baerial_2b69_3080e_2975fd93b16aec43b2725b36b527b85e944 f906f.jpg

[ER_BN]

If you are referring to the Moorabbin mid-air collision

43inches, thanks and my apologies...No, I was referring to the mid air at Gold Coast between two helicopters 02/01/23.

ATSB A0-2023-001.

[sunnySA]

Perhaps the real question is "how" rather than "who"?
On reflection, perhaps the question is why?

[PiperCameron]

Extrapolating ATSB's "concept"...to reality.

Were the helicopters fitted with ADS-IN?

Surely that crash showed the "limitations of see and avoid" as per ATSB?

Unless both aircraft were fitted with some kind of ACAS/TCAS (which usually doesn't rely on ADS-B anyway) or the pilots were using aural alerts on an EFB of some sort (Foreflight, etc.), I don't see what relevance ADS-B IN would have in prevention of that accident. Whilst flying VFR, it's important to keep eyes outside to maintain situational awareness - not stare at a screen and hope for the best.

There are bound to be recommendations for better SA coming out of that accident, and it will be interesting to see what those are.

[Mr Mossberg]

The GMH building is another one.

Agreed, that and Academy. Funnelling aircraft in to an aerodrome via points that nobody can spot anymore. Not real smart. So pilots are using their EFB to find an inbound reporting point as well as spot the other 3 aircraft that reported amongst your call.

[BronteExperimental]

Agreed, that and Academy. Funnelling aircraft in to an aerodrome via points that nobody can spot anymore. Not real smart. So pilots are using their EFB to find an inbound reporting point as well as spot the other 3 aircraft that reported amongst your call.
If nobody can spot them, then there ain’t much chance of two being in the same place then is there?

[compressor stall]

If nobody can spot them, then there ain’t much chance of two being in the same place then is there?
au contraire. Ever used Direct to function on a GPS?
and the head is inside looking at a screen… all the more likely

[Mr Mossberg]

If nobody can spot them, then there ain’t much chance of two being in the same place then is there?

I don't like putting people down in public, but you're not very bright are you.

Read what I wrote again slowly. Have a think about it. If you need me to break it down for you, let me know.

[43Inches]

Agreed, that and Academy. Funnelling aircraft in to an aerodrome via points that nobody can spot anymore. Not real smart. So pilots are using their EFB to find an inbound reporting point as well as spot the other 3 aircraft that reported amongst your call.

It's actually a very good point, watching a flight bag display, or even traffic display inside the aircraft takes a lot of time away from an effective visual scan. Very different to ACAS, which only alerts you when it detects a conflict. Another example of seemingly good technology that can work against safety in some respects.

[BronteExperimental]

I take your points, but you can’t have it both ways.
if someone is direct to the reporting point then chances are they do have their eyes outside. That’s a good thing.
if they are staring at an EFB then they may well have at least have some idea about potential conflicts. I agree that heads down direct to is probably a bit dopey. Is there any evidence to suggest this is what happens or are we just guessing? I certainly don’t do that.

What’s the proposed solution? No reporting points? Just call 3miles from the D anywhere?
do we think that improves things?

[Squawk7700]

I’m not even sure if YMMB tower can see ADSB traffic yet!

Can anyone confirm this?

When I got ADSB at about the start of the rebate period, they told me they can’t see anyone on ADSB.

[Traffic_Is_Er_Was]

Ever used Direct to function on a GPS
That's the thing isn't it. GPS is accurate. A published waypoint programmed in is essentially exactly the same spot for everyone. Using GPS the chances of being in exactly the same spot as someone else is proportionally higher than if just DR or visual nav was being used.

[PiperCameron]

That's the thing isn't it. GPS is accurate. A published waypoint programmed in is essentially exactly the same spot for everyone. Using GPS the chances of being in exactly the same spot as someone else is proportionally higher than if just DR or visual nav was being used.

Nah... The GPS might be accurate but some of these folks can't even FLY straight, let alone follow a magenta line VFR. :yuk:

Is it just me or is the size of the average Cessna circuit at YMMB getting larger these days?? I expect sometime soon they'll be outside 3 miles and turning base at Carrum with the rest of us.

[Clinton McKenzie]

I’ve been a bit busy and will catch up on some of the important earlier posts, but I have to say that – as with ADS-B IN - TCAS/ACAS is not the panacea either, at least not for aircraft in the vicinity of GAAPs – sorry ‘D Metropolitan’ - when they are busy. Lots of traffic in ‘close’ proximity.

When I started training and did flights in and out of YSBK, it was three parallel runways in operation, 3 aircraft rolling, 3 on short final, me on long final with an aircraft off each wing on final to the other runways, inbound traffic behind and outbound traffic in the general opposite direction (hopefully at least 500’ vertical separation). What do we think TCAS/ACAS would be doing during all of this?

As touched on earlier, it will be very interesting to see what avionics were fitted to the helicopters involved in the Seaworld tragedy.

[Traffic_Is_Er_Was]

Looking at the in chopper footage again, it doesn't appear that the pilot is particularly looking anywhere but outside. It's not like his attention is attracted to a particular instrument, and then he reacts by looking in the threat direction. He seems oblivious up to the moment of impact.

[43Inches]

Looking at the in chopper footage again, it doesn't appear that the pilot is particularly looking anywhere but outside. It's not like his attention is attracted to a particular instrument, and then he reacts by looking in the threat direction. He seems oblivious up to the moment of impact.

The collision threat is always the hardest to see as it won't have any relative motion, it will appear stationary to the target until the collision. The brain will pick up movement in the periphery relatively easily, to pick up collision course objects your scan needs to sweep the danger areas with periodic focus as you sweep. The helo pilot may have been alerted to something in that direction, but may not have considered it an immediate danger, just something being pointed out.

[Clinton McKenzie]

A video I saw included one of the pax repeatedly tapping the pilot on the arm/shoulder, apparently to alert the pilot of the proximity of the other helicopter. Did I misinterpret what I saw?

(The reason the avionics fit will be very interesting is if one or both of the helicopters had ASD-B IN with traffic alerting capability and, if it/they were, whether it was operational and, if not, why not. Remember: ADS-B IN is being advertised as something to assist VFR aircraft to avoid collisions.)

[43Inches]

A video I saw included one of the pax repeatedly tapping the pilot on the arm/shoulder, apparently to alert the pilot of the proximity of the other helicopter. Did I misinterpret what I saw?

(The reason the avionics fit will be very interesting is if one or both of the helicopters had ASD-B IN with traffic alerting capability and, if it/they were, whether it was operational and, if not, why not. Remember: ADS-B IN is being advertised as something to assist VFR aircraft to avoid collisions.)

Showing traffic and alerting conflicts are two different things. The pilot in the helicopter was in the aproach phase so traffic was probably low on the spectrum of threats. ADSB In would only have saved them if it was also fitted with ACAS linked to it.

[Squawk7700]

You saw and interpreted correctly CM, the passenger did indeed give a shoulder-tap as
a warning.

[43Inches]

You saw and interpreted correctly CM, the passenger did indeed give a shoulder-tap as
a warning.

Unfortunately without further input a shoulder tap to a pilot during flight could be interpreted as, 'what's that', 'where's the sick bags', and a hundred other things before one might think about colliding traffic. That in no way is saying the passenger should have done more, they probably had no idea how fast things were happening until just before things hit. So a shoulder tap is about all you would expect.

[Clinton McKenzie]

Why would traffic probably be low on the spectrum of threats in a helicopter in the approach phase in airspace used by other helicopters?

And if ACAS was necessary to have saved them, ATSB should be advertising ACAS as well, yes?

[43Inches]

Why would traffic probably be low on the spectrum of threats in a helicopter in the approach phase in airspace used by other helicopters?

And if ACAS was necessary to have saved them, ATSB should be advertising ACAS as well, yes?

Think about it from the point of view of a fixed wing pilot in the last 500ft on approach, are you looking for crossing traffic to suddenly jump out at you, or just on your runway alignment and possible conflicts on the runway.

As for ADSB IN, it depends on what you have hooked up to it for it to be useful, that could be an ACAS device or just flight bag traffic features, if its just flight bag traffic, are you going to look at that at 500ft on final?

I find traffic displays are pretty good when approaching a destination, until close to the circuit. After that things happen too quickly for you to be monitoring the displays, esp in heavy traffic. The radio and a good lookout are more important.

Also close to a circuit you will probably get a lot of alerts from irrelevent traffic, confusing the situation.

[Mr Mossberg]

What's the proposed solution? No reporting points? Just call 3 miles from the D anywhere?
Do we think that improves things?

Class D towers work in other parts of the world when you "call 3 miles" inbound. Would it work at Class D metro towers in Australia? More than likely not, so don't call them Class D towers. Call them GAAP and process the traffic accordingly. I'll tell you what doesn't work, inbound reporting points that have been swallowed by suburbia: GMH, Academy, Target, 2RN and the ridiculous Goodna. Try spotting Centenary Bridge unless you've been flying into AF for a couple of years. Still working: Park Ridge (but not for too much longer), TV Towers, Prospect, Carrum, Braaahton (and that can be confused at times).

I can tell you what IS happening is students (and most unfamiliar pilots) with their head buried in iPads inbound via stupid reporting points.

I did my CPL at Bankstown in the days that Clinton speaks of. It's no bull**** that you'd have 3 on final on each of the runways multiplied by 3 recurring. Why are these towers now not capable of handling the traffic they used to? At Bankstown you quite rightly used to get a bollocking if you flew a 747 circuit. You knew what you had to do. The eastern circuit at Moorabbin is a joke! Most of the circuits in these towered aerodromes are a joke.

[BronteExperimental]

Gee I dunno. Lots of ranting. No solutions. Not even sure what you’re perceived problem is. Everyone ends up in the same place at the same time eventually. It’s either a reporting point or base or final or the runway. Varying degrees of probability but all non zero in a busy metro area.

I think you’re suggesting we ban EC devices and other modern aids to SA and see what happens if we go back to the 70s.
I assume you’re adamant about what IS happening because you’re either doing it yourself or you’re in the cockpit with the student.
in either case it should be relatively straightforward to make a direct contribution to safety yourself.
I spend 5days a week at BK. Regularly see planes abreast.
maybe it’s not 3x3 because there just ain’t the volume of traffic of the good old days.
is that safer or not? I’m confused.

[Mr Mossberg]

Lots of ranting

:D :D

Yeah OK. It's all ranting.

​​​​​​​I’m confused.

​​​​​​​Yes you are.

[Clinton McKenzie]

Nobody is “suggesting we ban EC devices and other modern aids to SA”. For my part, I’m suggesting the benefits of ADS-B IN are being over-stated, and its limitations and traps are being under-stated, by the agencies plugging it.

[BronteExperimental]

Nobody is “suggesting we ban EC devices and other modern aids to SA”. For my part, I’m suggesting the benefits of ADS-B IN are being over-stated, and its limitations and traps are being under-stated, by the agencies plugging it.

100% agree with that.

[Traffic_Is_Er_Was]

So a shoulder tap is about all you would expect.
There was about 12-13 seconds from the departure of the helicopter until the impact with the other. Not much time to see it during a busy approach phase. If anything, the tap on the arm made the pilot look away from the threat. Impact was almost immediately after, so probably didn't change things too much though.

[Clinton McKenzie]

Perhaps I am completely misinterpreting what I saw, but what I think I saw was a second row passenger on the left side of one of the helicopters seeing the other helicopter getting closer from the left and below, and repeatedly tapping the pilot on the shoulder to bring the pilot’s attention to something the pilot wasn’t looking at. What I think I saw was a passenger trying to bring the pilot’s attention to an actual threat of which the pilot wasn’t aware. I anticipate that the ATSB’s report will recalibrate my interpretation if I’m wrong.

(Purely coincidentally, my pre-take-off brief to (usually non-pilot) pax is to ask them to be quiet during take-off but, if there’s something of which they think I need urgently to be aware, to tap me on my shoulder and point at what they think I need to be aware.)

Back to the main subject of this thread, it would be a ghastly irony of the one or both of the helicopters involved in the tragedy had ADS-B IN equipment with traffic alert capability, but switched off due to ‘nuisance’ alarms. I anticipate that the ATSB’s report will be clear about what avionics was fitted and how it was being used.

[BronteExperimental]

The preliminary already sheds some light on this.
But it’s ambiguously worded with little real detail.
TLDR one had an inop xpdr and we don’t yet know what the other had exactly.
Given they were 15-20yo airframes doing OCTA commercial ops VFR you can probably guess what they did (or more importantly did not) have fitted.

[Traffic_Is_Er_Was]

what I think I saw was a second row passenger on the left side of one of the helicopters seeing the other helicopter getting closer from the left and below, and repeatedly tapping the pilot on the shoulder to bring the pilot’s attention to something the pilot wasn’t looking at.
The in chopper footage which covers the 12-13 seconds from when the departing helicopter departs overhead the pad to impact has the left hand second row passenger just filming with his phone. He seems oblivious to the approaching chopper. The centre (?) pax is the one who sees the danger, and taps the pilot (vigorously I'll admit...as you would) immediately before impact. He basically taps the pilot and then grips the seat back in anticipation of the collision. What we can't hear is the audio. I'd imagine from his arm movements he's saying something and the pilot is not reacting. The shoulder tap is in desperation.
Two helicopters collide - Gold Coast, Queensland - Sea World 2/1/2023 - Page 9 - PPRuNe Forums (https://www.pprune.org/rotorheads/650560-two-helicopters-collide-gold-coast-queensland-sea-world-2-1-2023-a-9.html?highlight=seaworld) post #171

I doubt in the traffic scenario around Gold Coast scenics that any ADSB info was going to be taken notice of.

[Squawk7700]

I doubt in the traffic scenario around Gold Coast scenics that any ADSB info was going to be taken notice of.


How could an ADSB proximity alert NOT prevent this?

We just don’t have the tech yet to allow this. ADSB-IN has never been a focus for the government. Once the EFB’s put in the relevant alert algorithms with the audio routed through the intercom and everyone has an IN receiver, there would be half a chance. We are a long way from this happening though.

I’m sure the pilot would sit up and take notice of a loud beeping proximity alert came through his headset. Even FLARM would have worked well for such a small cost - it’s very suitable for such an operation.

[BronteExperimental]

Any of the newer avionics would have had PFDs lit up like a Christmas tree in this situation with audio alerts to match - providing there was indeed ADSB out. It seems that there was at best only one ADSB out here and even that is unclear.
I’ve flown behind IN/OUT for years and can attest that it’s extremely accurate and very functional in busy class D airspace . It’ll happily paint a dozen targets at a time all within a mile.
no need to have you’re head in the cockpit. It just calls them out.
Given the amount of pushback from industry just to introduce OUT, itll be ages before we get an IN/OUT mandate.
Maybe this incident will slowly move the needle.

[PiperCameron]

I’ve flown behind IN/OUT for years and can attest that it’s extremely accurate and very functional in busy class D airspace . It’ll happily paint a dozen targets at a time all within a mile.
no need to have you’re head in the cockpit. It just calls them out.

Sounds nice.. but what's the cost of that little setup?? Five figures at least, probably more.. and it still won't save you from someone like me charging around VFR with no ADSB-OUT. Sure, our beloved gov'mint has extended the rebate on fitment of these devices but it's still an expensive purchase (I suggest 70% might get more traction than 50%) with long lead times and to my mind the benefits and limitations aren't being advertised enough either as CM mentioned above.

If you really want to be safe out there, maybe IFR (where everyone has ADSB) is the only way to fly.. oh, hang on, did someone mention TIBA?? :rolleyes:

[43Inches]

Any of the newer avionics would have had PFDs lit up like a Christmas tree in this situation with audio alerts to match - providing there was indeed ADSB out. It seems that there was at best only one ADSB out here and even that is unclear.
I’ve flown behind IN/OUT for years and can attest that it’s extremely accurate and very functional in busy class D airspace . It’ll happily paint a dozen targets at a time all within a mile.
no need to have you’re head in the cockpit. It just calls them out.
Given the amount of pushback from industry just to introduce OUT, itll be ages before we get an IN/OUT mandate.
Maybe this incident will slowly move the needle.

The reality is that these things 'help' but also introduce new traps. The collision rates in the US are quite high despite having great radar and adsb coverage, and whats more a high percentage hapoen within actual controlled airspace. So ADSB IN/OUT helps, but its no magic bullet for the problem. And a lot of cases come down to lack of SA, poor communication and in some cases a reliance the automation would warn them.

Remarks like 'pfds being lit up' leads to pilots ignoring the chaff, so the warnings have to be timely, accurate and not spurious. I expect to get TAs close to busy airports, and once on final RAs are inhibited so all you get is alerts.

[BronteExperimental]

Sounds nice.. but what's the cost of that little setup?? Five figures at least, probably more.. and it still won't save you from someone like me charging around VFR with no ADSB-OUT. Sure, our beloved gov'mint has extended the rebate on fitment of these devices but it's still an expensive purchase (I suggest 70% might get more traction than 50%) with long lead times and to my mind the benefits and limitations aren't being advertised enough either as CM mentioned above.

If you really want to be safe out there, maybe IFR (where everyone has ADSB) is the only way to fly.. oh, hang on, did someone mention TIBA?? :rolleyes:
sure it’s not cheap, but try having an accident.
I get the affordability argument. For private day VFR I think it’s appropriate too.
All I’m saying is that the tech is available, it works when installed properly, and for a business running 4-5m of hardware turning over many 10s of millions a year carrying thousands of paying passengers, it’s harder to make the argument that 10k (or 20 or whatever) of avionics is not a cost effective safety enhancement.
Is it perfect? No. Is being on an IFR flight plan in G foolproof? Apparently not.
Like I said above, anyone who’s used this would agree with me that properly installed and operating IN/OUT would make this type of incident exceedingly improbable.

[Clinton McKenzie]

Any of the newer avionics would have had PFDs lit up like a Christmas tree in this situation with audio alerts to match - providing there was indeed ADSB out. It seems that there was at best only one ADSB out here and even that is unclear.
I’ve flown behind IN/OUT for years and can attest that it’s extremely accurate and very functional in busy class D airspace . It’ll happily paint a dozen targets at a time all within a mile.
no need to have you’re head in the cockpit. It just calls them out.
Given the amount of pushback from industry just to introduce OUT, itll be ages before we get an IN/OUT mandate.
Maybe this incident will slowly move the needle.Just so I understand what you’re saying about the functionality, when you have a dozen targets all within a mile (nothing surprising about that), which of them are ‘called out’ for you, on the basis of what criteria and what is the format of the ‘call’?

[BronteExperimental]

Just so I understand what you’re saying about the functionality, when you have a dozen targets all within a mile (nothing surprising about that), which of them are ‘called out’ for you, on the basis of what criteria and what is the format of the ‘call’?
Only traffic that is encroaching the “protected airspace” around you is aurally alerted. It’s rare to have more than one or two. At BK for example it’s usually choppers crossing over the top as you are on final or taking off that encroach. The volume of that changes depending on altitude/speed etc.
It’s hard to summarize the functionality of it. The hazard avoidance section of the pilots guide runs 50pages. If you want the prioritization hierarchy give that a read.
Suffice to say if you get an aural alert and a big yellow tennis ball appearing on your PFD you know exactly where to look and avoid.
It has been known to alert over the top of landing clearances so there’s some angst about that.
AFAIK I must be connected to an unswitched audio to stop people turning it off (intentionally or unintentionally)
that Alaskan midair where everyone was equipped was some kind of configuration or installation error like that on one of the aircraft.

[43Inches]

As I alluded to earlier even airline level TCAS is inhibited on approach and departure. At present the circuit area of an aerodrome is too chaotic for reliable solutions. TCAS/ACAS is great for en-route conflicts, but near airports its not going to do much but create a distraction of spurious alerts when you shpuld be heads outside monitoring your approach/flightpath and traffic, as well as a listening watch.

[PiperCameron]

As I alluded to earlier even airline level TCAS is inhibited on approach and departure. At present the circuit area of an aerodrome is too chaotic for reliable solutions. TCAS/ACAS is great for en-route conflicts, but near airports its not going to do much but create a distraction of spurious alerts when you shpuld be heads outside monitoring your approach/flightpath and traffic, as well as a listening watch.

If airline-level TCAS was all good for approach and departure, we wouldn't need tower controllers then would we?? (uhoh, maybe that's part all of Airservice's sinister plan...:E)

[Capt Fathom]

As I alluded to earlier even airline level TCAS is inhibited on approach and departure.

You sure about that?

[Clinton McKenzie]

Depending on the airport, some functionalities of TCAS are ‘inhibited’ by some crews on approach and departure. Some airports in the world are really, really busy. The content of 43’s post you quoted was probably an over-statement, but it’s not entirely inaccurate.

[43Inches]

Depending on the airport, some functionalities of TCAS are ‘inhibited’ by some crews on approach and departure. Some airports in the world are really, really busy. The content of 43’s post you quoted was probably an over-statement, but it’s not entirely inaccurate.

Depends on the fitment but generally TCAS will only show up to TAs once below a certain altitude. Its not generally a crew choice, its programmed into the system. You will still get a display of TAs and proximates. And in busy situations other and proximate locations can be a bit iffy on the display, most just a 'look here' type of thing rather than a radar you can use to avoid things. Aurals are also inhibited, for the reasons stated above about excessive distractions.

I think it comes back to the idea that traffic displays are a technology you can use in advance to identify threats and initiate communication to avoid conflict via radio and see and avoid. Again in a busy circuit its a distraction that will not help much.

And it cant be stressed enough that transponders fail or can be turned off, then the target will be invisible to any traffic display or ACAS.

[sunnySA]

And it cant be stressed enough that transponders fail or can be turned off, then the target will be invisible to any traffic display or ACAS.
Includes SSR radars. Primary radar will detect the target, but these are few and far between.

Of course, if the owner of the equipment fails to fix the kit...
B1352/23 REVIEW B994/23
RADAR COVERAGE, RADAR INFO SER AND RADAR BASED TRAFFIC INFO SER WEST
OF OAKEY (ROMA/GOONDIWINDI AREAS) NOT AVBL
DLA/RESTRICTIONS MAY OCCUR IN CTA
DUE OAKEY PSR/SSR FAILURE
FROM 09 110925 TO 11 220000 EST

[ER_BN]

When I posted the short initial comment regarding ADSB-IN / SeaWorld accident (post #43) I hadn’t anticipated the number and wide ranging contributions; so thank you for all your posts.

In my eyes the Sea World and Mangalore accidents are “bellwether” indicators of many of the issues / topics raised in many previous ATSB reports as well as the enormous number of posts on this and other aviation websites over the last 10 years.

I have been sent a copy of a technical paper (apparently available on the internet) that appears to be a production of two ATSB staff that was delivered to the ISASI conference in 2022.I believe it actually won an award for best paper at that conference. The paper under the name “From See and Avoid to Detect and Avoid” seems to be the basis for ATSB’s confidence and reasoning in their somewhat simplistic “marketing” for ADSB-IN for all VFR aircraft and the basis of this thread started by Clinton.

Some of the content also seems to be the source of graphical input in ATSB’s YouTube videos on the Mangalore accident, comparing the ground based TAAATS Eurocat STCA information with a prototyped ADSB-CDTI cockpit display.

An initial read of the paper and a review of the ATSB YouTube videos elicited the following doubts/issues:

1/. ATSB’s understanding of how the TAAATS Eurocat STCA functionality works and displayed is misleading, incorrect and definitely incomplete in the ATSB report and YouTube videos,

2/. ATSB’s ability to conduct proper investigations is severely hindered by their lack of knowledge and understanding of how TAAATS Eurocat works. A contributing factor to this is seemingly the lack of access to lossless video screen capture (TAAATS Eurocat Main/Auxiliary displays) coupled with synchronised air/ground and ground/ground audio. Evidence to be detailed in subsequent posts.

3/. Some of the concepts and graphical prototypes in the paper appear to have similarities in concept to an ADSB-IN cockpit product as described by BRONTË EXPERIMENTAL as per post # 72, as well as TCAS / ACAS general cockpit concepts.

4/. Some comments in the paper relevant to an investigation didn’t seem to be in the ATSB report, I will have to do a forensic examination of both.

More to follow…

[Clinton McKenzie]

I’ve been trying to get my head around the implications of your latest post and your post at #31 ER BN. My ‘take’ is that you have deep expertise in the area and you have no confidence that what’s presented in the ATSB report on the Mangalore tragedy is an accurate representation of what really happened or what the controller saw in relation to SCTAs. It my take correct?

Notwithstanding that I have no expertise in the specific ATC system displays and functionalities, it makes no sense to me that ATSB went to the trouble of recreating what ATSB represents as the display showing the velocity vectors as not intersecting at the time of what the ATSB describes as the 1122:49 STCA but decided not to recreate the display showing the velocity vectors at the time of what ATSB describes as the ‘final STCA’ at 1123:51 - immediately preceding the collision.

[Clinton McKenzie]

ATSB’s interim report of its ongoing investigation into the Sea World tragedy is already telling as to the limitations of anti-collision gizmos, particularly when they are not serviceable or are deliberately or unknowingly configured to filter out what are assumed to be ‘nuisances’. Key extracts, with my underlining:VH-XH9 conspicuity devices

While operating in NZ, the helicopter was fitted with an L3 Lynx NGT 9000D+ transponder with Automatic Dependent Surveillance–Broadcast (ADS-B)-out capability on 27 September 2022. At that point the unit appeared to function with recorded data matching records of flights undertaken in NZ up to 19 October 2022.

Details of the new registration were to be updated in the unit, and some problems doing so were encountered. For flights from 2 December 2022 to 26 December 2022, externally recorded ADSB data was either showing no data (4 days) or the old NZ registration (11 days). From 27 December 2022 the new Australian registration was recorded but all tracking within Australia was intermittent.

Additionally, on 20 December 2022 air traffic control at Gold Coast Airport could not identify XH9 on secondary surveillance radar. Following this, pilots were aware that they would not be accepted into controlled airspace in XH9 without a functioning transponder. Troubleshooting of the transponder was not complete at the time of the accident. During inspection of XH9 post-accident, the ATSB lowered the belly panel and found that the transponder antenna was disconnected.

…
The word “disconnected” is in an interesting one. It’s not one I would use if, for example, the antenna coax had been pulled out of the back of its fitted connector due to, for example, impact forces. I interpret it as meaning that the fitted connector remained on the antenna coax but it was not connected to the antenna. If that interpretation is correct, maybe the antenna had, in the course of fault finding or other maintenance, been deliberately disconnected and left disconnected, or not reconnected properly such that it vibrated loose and disconnected in subsequent operations.

I note that the installation manual for the L3 Lynx NGT 9000D+ system includes these CAUTIONS among others:1. Operating the unit with the GPS antenna connected and the L-Band antenna NOT connected may damage the unit.

2. All antenna connections must be connected prior to operation.My understanding is that the L-Band antenna is used to transmit/receive, among other frequencies, 1090 mHz – the frequency used for transponders and ADS-B in Australia. Happy to stand corrected. All of the avionics with transmitters that I’ve worked on could be damaged if they transmitted into the wrong impedance and, in any event, if no antenna’s connected the transmission doesn’t go far.

VH-XH9 detection equipment

The L3 Lynx NGT 9000D+ also provided traffic advisory (TA) alerts. The unit could visually display traffic although this was not configured. In addition, the system was also not linked to another display, therefore it gave audible alerts only. Pilots would hear warnings such as ‘traffic, traffic, 3 o’clock high, 2 miles’.

There were two sensitivity levels, A and B. Sensitivity level A reduced the number of nuisance TAs during take-off and landing. Sensitivity level B maximised the detection of TAs during the cruise phase of flight. If the aircraft was at or below 1,700 ft above ground level (AGL), the traffic advisory system (TAS) would not display or calculate alerts for other aircraft which were determined to be on ground (not airborne). Intruders determined to be below 380 ft AGL were considered to be on ground.

A configuration option called ‘Ground Filtering Altitude’ allowed the user to set the on ground (alternate) determination for 5 ft instead of 380 ft AGL.

At the time of publishing, the exact settings of this unit had not been determined and analysis is ongoing.

…My interpretation of the ATSB’s language here is that the TA alerting system was working in principle during the flight – “provided … alerts”; Pilots “would hear warnings” – and the only remaining question is whether the ‘ground filtering option’ was or was not configured such that XKQ would have a generated an alert. But I don’t see how the TA alerting system would have been working at all if XH9’s transponder antenna was disconnected. Again, happy to stand corrected if I’ve misconstrued ATSB’s language or misunderstand the technical consequences of XH9’s transponder antenna being disconnected.

(And I cannot help but point out the truly ghastly irony that these systems are deliberately designed and configurable to filter out the ‘nuisance’ of being warned about the very kinds of circumstances in which this collision occurred.)

VH-XKQ conspicuity equipment

…

XKQ was equipped with a Garmin GTX327 Transponder which was detectable by secondary surveillance radar and was detected on the day of the accident.

VH-XKQ detection equipment

The helicopter was fitted with an Avidyne TAS600 TAS. The system had a ground mode and a flight mode. It would automatically switch between the 2 as the aircraft climbed or descended through 400 ft. In flight mode, when a detected intruder met the criteria for TA, the system used an annunciator light (marked ‘Traffic’ or ‘Traffic Alert’) and an audible voice annunciation. The announced phrase was preceded by a tone and began as ‘Traffic’, the clock position of the alert was given, and then the relative altitude of the intruder and range was announced. It was reported that no annunciator light was present in XKQ.

When the host aircraft descended below 400 ft AGL, the system transitioned to ‘ground mode’ and TA announcements were muted. While XKQ was on the ground, the TAS600 would be in ground mode. Aural annunciations would be muted and the aircraft did not have an interface from the TAS system to a display. After departure on the accident flight, XKQ did not reach an altitude that would have triggered the TAS600 to switch to flight mode.

…XKQ’s system was deliberately designed not to give an alert in the circumstances, even if XH9’s transponder had been working properly.

I look forward to seeing if the ATSB concludes that the much-hyped ADS-B IN functionality would have prevented this collision and terrible tragedy, and why.

[BronteExperimental]

XH9s Lynx (even if its antenna was plugged in, turned on, its configuration appropriately done etc ) wouldn’t have detected XKQs transponder anyway as the GTX327 is Mode A/C/(maybe S) only not ADSB out.

If XKQs xpdr was an ADSB out then you would expect an appropriately installed, configured and tested Lynx in XH9 to have alerted.

There’s a litany of failures here with equipment installation and setup that’s only been very superficially covered in this report. When was the last transponder check? Other than the pilots working out it didn’t work or was flight IDing the last rego. Was the MR endorsed?

Most of these issues should have been an easy fix for any half competent avionics tech. It beggars belief that XH9 was flying around in commercial ops with the Hex not updated and/or just turned off and then had a “disconnected antenna”. I think there are some rules about that somewhere…

according to the report they still haven’t determined the status of the ground filtering altitude. Is the unit damaged? That’s 3 button presses.

it’s all moot anyway as XKQs avionics were never going to be of any use for ADSB.

ADSB IN/OUT is extremely powerful and having flown with it for many years in lots of busy airspace, I have no doubt that had both aircraft here been equipped with it then the outcome would have been different. The sad reality is that it’s going to be decades before there’s lots of IN unless it’s mandated.

Like I mentioned before, for me the real question here is what’s an appropriate amount of equipment (and inspection regime) for an operation that carries thousands of fare paying passengers a year? It’s less than what you need to fly IFR in private ops. That makes no sense to me.

I have to have a passenger warning that says my experimental doesn’t comply with the same safety standards as “normal passenger commercial flight”
Does the average passenger think that the sea world scenic is a “normal passenger commercial flight” (their interpretation- not CASAs) and has the same level of safety thereof?

[Clinton McKenzie]

< ADSB IN/OUT is extremely powerful and having flown with it for many years in lots of busy airspace, I have no doubt that had both aircraft here been equipped with it then the outcome would have been different. >Just so I understand, during all of that flying were the ADSB IN/OUT systems you used configured to provide alerts when your and other (suitably equipped) aircraft were below e.g. 400'?

[BronteExperimental]

Just so I understand, during all of that flying were the ADSB IN/OUT systems you used configured to provide alerts when your and other (suitably equipped) aircraft were below e.g. 400'?

It’s hard to be very specific about the altitude.
There is no configuration in my setup (Garmin) for excluding alerts based on any arbitrary altitude.
Im experimental so I can turn them off entirely if I like. I choose to leave them on.

What I can say from experience is the following things do alert:
If I’m on base and there’s someone on base on the parallel runway, that’ll alert. I couldn’t be precise about altitude in that case. That’s unlikely to be sub 400’ tho.
If there’s a crossing chopper low at mid field - which is very common and has had more than one near miss - that’ll alert. I dont know what altitude they are at, but I’m on the ground at flying speed or close too it airborne and climbing at 500-1000fpm.
A common one is me just after rotation with a trainer in the southern circuit on upwind. I’m definitely sub 400’ there - but with a high closure rate.

What doesn’t alert is me on short final with a stationary aircraft at the holding point. though they are painted brown for ground.
likewise - final for center with a plane on each side. That is rare though.

All of the ADSB OUT equipped aircraft are most definitely painted on the MFD (and PFD in synthetic vision if in front) regardless of whether the system determines they are worthy of auraly alerting or not.

A general observation is that it’s a pretty conservative setup. In jurisdiction(s) where installation rates are somewhat higher there are complaints about this.

Slight off topic but relevant. TCAS direct interrogation of mode C is obviously very outdated technology with lots of limitations. This is where all of the altitude based muting and the like comes from. In helicopters it’s particularly acute as they can change heading rapidly while potentially not changing course. This has made latency and extra sensors and as a worst case suppression important variables.
ADSB alleviates the vast majority of these concerns. ​​​​​it’s trivial for the boxes to determine the probability of aircraft being in proximity in the future.

To bring this back to the original thread conjecture.
The sad reality of ATC in this country is a bloated ineffective infrastructure that is literally decades behind the state of the art in many ways. The mangalore accident is an absolute tragedy. Most can read through the obfuscation and weasel words to get to the underlying human error.
The regulator clearly knows this but will never explicitly state it.
Regardless of what the controller told me (or didn’t) if I had repeated STCA equivalent on my ADSB IN (noise in my headset and a big tennis ball on my PFD - CDTI in bureaucratic gobbledygook) I sure as **** would be unilaterally arranging my own separation pronto regardless of airspace classification.
Which is your point…

[Clinton McKenzie]

My point was more that your categorical statement that "had both aircraft here been equipped with [ADS-B IN] then the outcome would have been different" should, I think, be tempered a bit with some qualifications: The equipment must be serviceable, the equipment must be configured to give alerts in these frequently low level and frequently close proximity helicopter operations and the pilots must be trained to know how the equipment works and not to ignore alerts.

My (inexpert) guess is that the number of alerts in those kinds of operations would quickly result in configuration selections to filter them out. That's why I look forward to seeing if the ATSB concludes that the much-hyped ADS-B IN functionality would have prevented this collision and terrible tragedy, and why.

[Squawk7700]

I guess with them landing literally a stones throw from each other, it would need to be highly configurable, or you’d simply just have to turn it off.

[Clinton McKenzie]

That's what I figure.

[MechEngr]

"In helicopters it’s particularly acute as they can change heading rapidly while potentially not changing course."

If heading is derived from GPS the GPS has no idea the orientation of the fuselage relative to direction of travel.

[Clinton McKenzie]

I think BE was there referring to potential collision info derived from Mode C data alone, which does not include GPS position and the calculation of position done by other equipment is 'less instantaneous' than with Mode S / ADS-B?

[BronteExperimental]

Yes I think we are on the same page.
ADSB doesn’t require heading information other than to orient an IN display - if there is one.

mode C based TCAS is a whole other animal.
heading sensors, directional antennas on the top and bottom of the aircraft, baro alt etc.
In helicopters this is more complex for many reasons.
for example the belly mounted directional antennas are useless near the ground or water - where helicopters are more likely to be found. Hence the inhibiting close to the ground due to spurious reflections.

It was good technology for the day. It’s been superseded. I doubt anyone would argue that point. Fitment and usage though…