Apparently midair at Gympie at 3pm today, 9/11/22

[Dermot McD]

Quote

Had each aircraft been fitted with ADS-B IN, and a suitable cockpit display, the occupants would have received the same quality of surveillance information received by the controller.

The above sentence could just as easily state: "Had each aircraft been fitted with FLARM, and a suitable cockpit display, the occupants would have received a better quality of surveillance information than received by the controller." I'm not saying ADS-B is useless (thought it is unless almost everyone has it), I am just say for the benefit of those who do not use it, that FLARM is actually a better system and it's a shame that this was not adopted.

 

This is from the FLARM website: "FLARM works by calculating and broadcasting its own future flight path to nearby aircraft. At the same time, it receives the future flight path from surrounding aircraft. An intelligent motion prediction algorithm calculates a collision risk for each aircraft based on an integrated risk model. When a collision is imminent, the pilots are alerted with the relative position of the intruder, enabling them to avoid a collision"

 

Isn't this a VHS and whatever that other technology was. VHS was inferior in almost every way but it triumphed (aided by the porn industry.)  Have you flown with FLARM? Almost all gliders are required to have a functional FLARM while unless the rules have changed, GA aircraft are not and last time I looked had an installation rate of about 5% which makes it worthless in most situations because it obviously works only if both aircraft have it.  

 

And regarding radio, I fly power and gliders, both VH registered but being an amateur flyer, I try to use correct radio communications with communication being the important part. My radio comments were about poor practice by many VH registered power pilots, perhaps hoping that RA pilots were better. I have no problem at all with commenting that many, if not most VH pilots regularly omit or garble their location since most if not all my RPT friends say the same thing.

 

D

[Carbon Canary]

On page 1 of this thread I mentioned I had ordered avionics for traffic.

 

Here is the blurb from the manufacturer :

 

AIR Traffic transmits and receives FLARM® data. Additionally, AIR Traffic receives ADS-B and Mode-S traffic data (It is only capable of computing the horizontal and vertical range of Mode-S traffic. The direction of Mode-S targets is not detected). 

 

I won’t get to test the gear for at least 12 months so I’m hoping I made the right decision. The unit will be connected to a Kanardia Nesis iii display.

[kgwilson]

The ADSB receiver in the SE2 sends the aircraft data including height AMSL and its current location to the connected display software on the moving map. The moving map therefore displays the direction of travel and can then estimate current speed and determine if there is a possible conflict. As I have mentioned the free software I have been using on my phone & tablet shows the ADSB data (rego, Height) from the aircraft in range (up to 40NM away) in green when it determines from its calculations there is no conflict and yellow when there is possible conflict and an alarm in red when there is probable conflict.

[Garfly]

I believe that all ADSB altitude encoders (like Mode C) work on the basis of Pressure Alt. - effectively, Flight Level -so that all aircraft are on the same pressure datum (necessary for self separation by cockpit display).  This would typically vary by several hundred feet from AMSL values.  I've read that ATC automatically correct the PA values for QNH below the transition level and that this is partly why controllers routinely check on the correction by requiring pilots to report altitude.  Maybe some of our ATC people could confirm and/or enlighten us on this point.

 

 

 

 

Edited December 7, 2022 by Garfly

[Kyle Communications]

The SE2 just has a super accurate GPS in it The TailbeaconX and AV-30C I just got the TailbeaconX itself has that same gPS in it but the AV-30C has the calibrated preassure sensor so it is TSO compliant. You need both together or some other Pressure encoder to complete the TSO package

 

 

[Garfly]

 

Yes, and I guess the AV-30C (which is an installed PFD instrument) is also plumbed into the aircraft's pitot static system.  The SkyEcho2 is measuring its Pressure Altitude from the cabin where it's mounted and that can vary  - even in basic aeroplanes - from static port values. So there's another possible error right there.  But we're not using the device to 'just-miss' conflicting traffic vertically in IMC.  And, in any case, all indications are rounded to the nearest 100'.   

Whenever unknown traffic shows up on the screen with 00X relative altitude (i.e less than 1000') I reckon it's time for a good look outside in the indicated direction.  (To me the 00 stands for "Uh, Oh!"   ;- ) 

[coljones]

On 07/12/2022 at 10:31 AM, Dermot McD said:

........ They're OK tools but I find it baffling that regulators cannot get themselves together and include the superior functionalities of FLARM with ADS-B etc in one reasonably priced device.

The SE2 is a very effective front end to a variety of apps - it provides an ADSB-out signal that contains an accurate GPS position (lat, long, height and ident) and receives similar ADSB-In info from all ADSB-out equipped A/C in range. 

 

What is required is to get some smarty to integrate the Out and In info in plane to produce an accurate system to provide proximity alerts. 

 

The beauty of SE2 (and some other ADSB systems) is that it does not depend upon ground stations or mobile towers (and which suit your SIM card). 

 

I may have missed it but there are some smart people out there doing majik things with Raspberry Pis and who may have already built an ADSB Prox detector that doesn't require one having one's head inside the plane staring at a tablet screen. 

 

I'm not sure that an ADSB prox device could/would/should be built by the regulators.

[Garfly]

 

(We already have our own smart guy on the job ;- )

 

[coljones]

23 hours ago, kgwilson said:

..... As I have mentioned the free software I have been using on my phone & tablet shows the ADSB data (rego, Height) from the aircraft in range (up to 40NM away) in green when it determines from its calculations there is no conflict and yellow when there is possible conflict and an alarm in red when there is probable conflict.

"Free" - sweet words to my ear.  What app/product are you using?

[kgwilson]

2 hours ago, coljones said:

"Free" - sweet words to my ear.  What app/product are you using?

Enroute Flight Navigation from Google Play. Created by some German Aviation students. Has constant upgrades & updates. It is simple without lots of fancy features you don't really need. Try it. Doesn't cost anything & has a good manual as well.

[Bosi72]

3 hours ago, Garfly said:

 

(We already have our own smart guy on the job ;- )

 

We already have that functionality in AvPlan (and likely in OzRwys).

 

 

[Garfly]

 

 

4 hours ago, Garfly said:

(We already have our own smart guy on the job ;- )

1 hour ago, Bosi72 said:

We already have that functionality in AvPlan (and likely in OzRwys).

 

Yes, and even aural alert functionality running EFBs with AvTraffic https://avtraffic.com/#  

But I think RFguy's experiments aim to take all that to another level.  To quote him:

 

 

"... yeah it's easy enough to do a proximity alert with gps XYZ available ... //

 

... future motion can be described with a simple set of equations like new location = old location + velocity and direction.  One second is a pretty good update rate so it doesn't have to guess much, just project a trajectory.   As an object gets closer, it's worthwhile making the algorithm leaky, such that older fix points are weighted lower in the prediction, and the most recent updates weight more heavily. //

 

... essentially - how it works  

 

1) Acquire time series location data  (from ADSB receiver from other aircraft)

2) apply a Kalman filter to that data to get the most likely values- since the raw location data from the ADSB probably has a random magnitude of 5m in XY and 10m in Z.

3) Now we have cleaned data, apply the data to a non linear regression  prediction tool . There are many - and quite sophisticated tools and algorithms. 

4) predictions are done, paths drawn in 3d space, and  for each combination of airplanes, distances calculated as a time series to provide a probability of a conflict

 

Think of the use of a Kalman filter as a zero lag  averaging tool."

[Bosi72]

That would be great to have, especially for airshows, or aircrafts operating in aerobatic areas, where paths are based on aerobatic sequences. 

 

Just as an example, below is the path of Extra NG operating in various directions both vertically and laterally, in a short period of time, within 1km x 1km x 1km box, between 3000ft and 1500ft, and speeds between 250kt and 60kt.

 

https://flightaware.com/live/flight/map/VHOPK/history/20221203/0129Z/

 

There is a software which does that, embedded in air-air missiles, however even that software has misses.

 

Personally, proximity alert is good enough for me to start thinking what to do next.

 

Look forward to see the development of the trajectory projection app.

 

[aro]

I have been flying for a few years with Avplan + ADSB receiver. These are my observations:

 

It's very useful IF the other aircraft is travelling in a straight line and/or you know its intentions. For example, if you are both inbound to the same airfield from the same direction you can get a much better idea of your relative positions and whether you need to take any action to ensure separation. Likewise, yesterday I was inbound to an airfield about 20 miles out when another aircraft departed on a reciprocal track. I was able to delay my descent until we passed each other so I wasn't descending into their path.

 

It can also provide a useful picture when you are arriving at an airfield, supplemented by radio e.g. you might "see" 3 aircraft in the circuit, plus another on the radio but without ADSB, and another on ADSB 2 miles ahead inbound. That's a useful aid to situational awareness prior to arriving.

 

When it's not so useful:

• If the other aircraft is not travelling in a straight line.
• Once you are close enough that separation is an issue e.g. less than about 1 mile. By that point you need to be looking outside for the aircraft. It's easy to see why controllers working with a screen use a separation standard of several miles.

It's also very tempting to try to separate yourself when there is no risk of collision. This is surprisingly difficult because when you are in reality a long way apart any change to your track doesn't make much difference on the screen.

 

On 07/12/2022 at 1:07 PM, Garfly said:

In its report on the tragic collision of two light-twins over Mangalore in early 2020, The ATSB observed:

 

"Had each aircraft been fitted with ADS-B IN, and a suitable cockpit display, the occupants would have received the same quality of surveillance information received by the controller. This technology could have prevented this accident from occurring ... // The ATSB also notes that ADS‑B receivers, suitable for use on aircraft operating under both the instrument or visual flight rules, are currently available within Australia at low cost and can be used in aircraft without any additional regulatory approval or expense."

I wouldn't read much into that report. IFR aircraft need separation by ATC, that is what it was invented for, but for some reason we don't do it in Australia. The report deliberately ignored that. I don't think that having additional traffic information in the cockpit (other than last resort stuff like TCAS) will make IFR safer. There have been a number of incidents with IFR aircraft trying to do DIY traffic coordination in Australia (including RPT), but the obvious conclusions are ignored.

 

"the same quality of surveillance information received by the controller"

 

Since Mangalore, ATC has been a lot more proactive trying to avoid traffic conflicts in G airspace. It's pretty painful to listen to. Basically the quality of surveillance information isn't the problem - the problem is that separating aircraft using a screen is very difficult unless you know the intentions of all the participants, can make a plan and give people instructions i.e. ATC.

[facthunter]

Vertical separation is  the most reliable, provided you know about Altimetry and have the same BARO reference and the thing is within limits. Mistakes have been known to occur with assigned levels and that possibility should be eliminated. Flying more accurate tracks make everyone fly in closer proximity IF they don't fly OFF route a bit  There ARE things people can do to  reduce risk. Nev

[aro]

11 minutes ago, facthunter said:

Vertical separation is  the most reliable, provided you know about Altimetry and have the same BARO reference and the thing is within limits.

Vertical separation is most reliable, as long as no-one needs to climb or descend and the altitudes are available/usable. Once you need to climb or descend, an accurate understanding of aircraft locations is required.

 

One day I was listening on area as 4 IFR C172s departed Ballarat for Avalon, closely followed by an IFR Seminole. The IFR traffic information from ATC was entertaining. It was clear blue sky so no problem to actually separate VFR, but good luck sorting that out with pilot organized separation if it was IMC with a low icing level.

[facthunter]

  ATC "Opposite direction traffic  1000 feet below, estimated time 12.  Report sighting and passing ".. Plenty of times communicating with other aircraft is done at Pilot's initiative  OCTA in IMC. It's YOURs and other's lives depend on it. and it's high workload.   Nev 

[aro]

19 minutes ago, facthunter said:

Report sighting and passing

You need to assume sighting isn't possible IFR. It also doesn't work for multiple aircraft inbound on the same track to the same destination - particularly when the fastest one is at the rear!

[facthunter]

All flight abv FL 210 is technically IFR. IF it's possible you use it and you'd be surprised how often you can do it. There are other (instrument derived) ways but they allow greater tolerances. Overtaking traffic has a rate of closure if it's faster and overtaking. The best example/ application of reliance on vertical separation is in holding patterns where multiple aircraft may actually be on top of others at times.. Nev

[Garfly]

6 hours ago, aro said:

I have been flying for a few years with Avplan + ADSB receiver. These are my observations: It's very useful IF the other aircraft is travelling in a straight line and/or you know its intentions ....   ///   .... When it's not so useful:

• If the other aircraft is not travelling in a straight line. •Once you are close enough that separation is an issue e.g. less than about 1 mile. By that point you need to be looking outside for the aircraft. //  ...  It's also very tempting to try to separate yourself when there is no risk of collision. This is surprisingly difficult because when you are in reality a long way apart any change to your track doesn't make much difference on the screen.

I don't think I understand the point you're making Aro.  I'd have thought that a threat approaching close enough for separation to be an issue would go on the useful side of the ledger. What if you're in a high wing and the airprox target is a low wing descending on you from behind, a glance at your iPad screen (as into your rear vision mirror) might be the ONLY thing standing between you and disaster. What's the point of looking outside if you don't know where to look; if the other aircraft is, at that moment, invisible to the eye, for whatever reasons. 

 

I've probably experienced a half-dozen unexpected close encounters with other aircraft over the years and in each case the threat emerged out of the blue yonder in a matter of seconds and had whizzed past before any kind of reaction was even thinkable.  And you can find dozens of real-life, close-call videos online that all tell exactly the same story.  Which, BTW, is why I've always thought of the "clearing turn" as one of aviation's most fervent Hail Marys. It's often done as a ritual, as if just performing it will give some kind of magical protection - never mind that it was done 5 minutes ago and that jet bearing down on your stall practice has travelled 20 miles since the last, ahem, 'clearing'.

 

Also, I don't get the difficulty that you seem to see with "self-separation ... because when you are in reality a long way apart any change to your track doesn't make much difference on the screen."  In my experience you can easily judge quite small deviations. ADSB updates every second or so and any threat icon will have a little arrow showing its current direction (plus altitude and vertical trend) and you own ship icon has a longish pointer line indicating clearly where you're headed. The whole situation can be grasped in seconds from the picture on the screen (far better, quicker, safer SA than the best radio chat has to offer.)  And I don't see a problem with threat targets not sticking to straight lines. A mere glance updates the danger just as it does with the big semi bearing down on you in the rear view mirror.  You see. You avoid.

 

Anyway, you give a good example of all that from your own experience: 

"yesterday I was inbound to an airfield about 20 miles out when another aircraft departed on a reciprocal track. I was able to delay my descent until we passed each other so I wasn't descending into their path."

 

For sure, there are down-sides to all 'simple solutions' it's just that I haven't come across the same ones you have with SE2, in practice.  Of course, the problem remains that the majority of the GA/RA fleet are not ADSB equipped. But that's changing slowly and, anyway, just being able to see and avoid RPTs and flying doctors, alone is definitely worth the price of admission.

 

Anyway, in an earlier post I quoted from the ATSB Mangalore report, thus:

 

"Had each aircraft been fitted with ADS-B IN, and a suitable cockpit display, the occupants would have received the same quality of surveillance information received by the controller. This technology could have prevented this accident from occurring ... // The ATSB also notes that ADS‑B receivers, suitable for use on aircraft operating under both the instrument or visual flight rules, are currently available within Australia at low cost and can be used in aircraft without any additional regulatory approval or expense."

 

 

And you said about that:

6 hours ago, aro said:

I wouldn't read much into that report. IFR aircraft need separation by ATC, that is what it was invented for, but for some reason we don't do it in Australia. The report deliberately ignored that. I don't think that having additional traffic information in the cockpit (other than last resort stuff like TCAS) will make IFR safer. There have been a number of incidents with IFR aircraft trying to do DIY traffic coordination in Australia (including RPT), but the obvious conclusions are ignored.

 

Again, I'm not quite sure where you're coming from here.  It seems to me you are reading too much into the report.  Or perhaps into my juxtaposition of those few selective quotes.  Of course, IFR ops in general have little to do with us recreational types.  Anyway, I took those passages in the report to suggest that although those aircraft were on IFR plans they were effectively operating in VFR conditions - they would have been cleared to descend into the badlands of G space, I presume. Just like very many commercial flights do every day. These are places where aircraft on IFR plans - but in VMC - need to arrange their own separation from the hoi polloi - and from each other. This is still - for good reasons - done mostly by radio but I think the writers of that report were just moved to point out that even the most basic sub-1K SkyEcho box hooked up to the iPads in the cockpits of those two twins  "could have prevented this accident from occurring ..."    They were not trying to say that ADSB IN/OUT was all that was needed for IFR self separation.  And the UAvionix company very clearly states that the SkyEcho2 is provided ONLY as an aid to traffic awareness by VFR pilots in VMC.   IFR and IMC have nothing to do with it.

 

 

 

 

Edited December 11, 2022 by Garfly

[aro]

14 hours ago, Garfly said:

I don't think I understand the point you're making Aro.  I'd have thought that a threat approaching close enough for separation to be an issue would go on the useful side of the ledger. What if you're in a high wing and the airprox target is a low wing descending on you from behind, a glance at your iPad screen (as into your rear vision mirror) might be the ONLY thing standing between you and disaster.

The problem is that there is always a lag. It's unavoidable. You say ADSB updates every second, but that update isn't necessarily received. Avplan will display traffic less than 90 seconds old - which means any position displayed could be up to 90 seconds old. SkyEcho will have similar logic, but I don't know how many seconds.

 

Unless you have dual external antennas on top and bottom there are probably blind spots on your aircraft. Probably behind you, if the device is in the cockpit. I don't know the specifics, but I suspect at ADSB frequencies, the receiver can't see through metal structure any better than you can.

 

So the picture it is displaying is always an approximation. Worst case, aircraft could be more than a mile from the displayed position.

 

Again, this is something I have seen. An aircraft was showing 2 positions, the one received via the internet, and an ADSB position. That's not uncommon, but usually the ADSB position is in front i.e. more recent. This time the ADSB position was about a mile behind the internet received position. So for some reason (e.g. antenna shielded by structure) the ADSB update wasn't received.

 

So once you are working with traffic at close range (the circuit etc.) you need to see the traffic. It's Visual Flight Rules - you need to separate visually. ADSB is like the radio - its an aid, to make finding traffic visually easier.

 

If you have traffic behind you that you can't see, you need to trust them to be looking out the window so they can see you. And you need to give the traffic in front the same courtesy.

 

15 hours ago, Garfly said:

A mere glance updates the danger just as it does with the big semi bearing down on you in the rear view mirror.

No, it is not like a rear view mirror - that is the point. A rear view mirror is real time visual information. ADSB is information from some time in the past - maybe 1 second ago, but up to e.g. 90 seconds ago.

 

I'm not suggesting that these systems shouldn't be used. They provide useful information and I will keep using it. But they are not a magic box. Like any other system, they have limitations. Understanding the limitations is the key to improving safety rather than degrading safety.

[Garfly]

Aro, you are misinformed.  ADSB works aircraft to aircraft. There is no significant latency due to a 'similar logic' to internet based traffic displays.  Nobody here thinks it's magic.  It's science. We agree on one thing, though, "understanding the limitations is the key to improving safety rather than degrading safety."

[Kyle Communications]

ARO  there are 2 types of ways the info comes in for ADSB in..one via your ipad trough one of the nav programs is via your sim card via the internet..yes that has lag that is not fixed. The real advantage of true ADSB in and out of the aircraft is realime millisec data refresh direct between all aircraft in the respective eqyuipments range that yo have in your aircraft. That realtime is sent to your Ipad and is usually a different colour target. The sim card targets are blue the direct targets are red

 

[aro]

1 hour ago, Kyle Communications said:

ADSB in and out of the aircraft is realime millisec data refresh direct between all aircraft in the respective eqyuipments range that yo have in your aircraft. That realtime is sent to your Ipad and is usually a different colour target.

Yes I know... on Avplan the ADSB targets are green and the network targets are blue.

 

But there is no guarantee you receive the ADSB broadcasts. They work on a frequency that is easily blocked by aircraft structure. So e.g. if a low wing aircraft with the ADSB antenna on the bottom turns towards you, placing the whole aircraft between you and their antenna, maybe the ADSB stops updating. Your own aircraft structure can also shadow the ADSB signal.

 

Some ADSB systems have an antenna on top as well as on the bottom. These are designed for more reliable air-air signals rather than the air-ground design of regular transponders. But they are more expensive and probably not regularly installed on GA aircraft.

 

Like I said, I have seen the green air-air ADSB target about a mile behind the blue air-ground-internet-ipad target. Most of the time the ADSB target will be up to date (although how frequently does the display update is another interesting question). But its not 100%.

 

[Kyle Communications]

ARO  the update rate for ADSB is literally millisec....why the direct tartget is appearing behind the sim card based target I have no idea at all. The direct target is the one I would believe for real time. Also even with some blocking any aircraft with a external transponder antenna will give you at least 10 to 20nm direct hits. The SE2 works from 10 to 40nm and seems to do reliably with just a pcb etched antenna. A external antenn fitted to to the SE2 I have performed tests on 2 aircraft now with external antennas fitted and saw up to 180km for the SE2 on detection of other aircraft to aircraft hits