Originally Posted by
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: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 verypurpose 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.