Musings on traffic detection

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Rich
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Musings on traffic detection

Postby Rich » Thu Aug 09, 2018 12:05 am

There are those that decry reliance on electronic detection of real and potential traffic conflicts. I would agree that there is the potential of missing a potential conflict (for whatever reason) by not paying attention out the windscreen. But I submit at the very least equal weight needs to be given to both sources of data:

- Some aircraft have abysmal outside visibility in various directions. PA12/22's, for example, are truly terrible. But this is typical of many designs based in the 1930's (Cubs, Champs, including newer variants of this mindset: Carbon Cubs, Maules, etc.).
- Even A/C with a reputation for great visibility (such as our Diamonds) have their limitations. How well can you see behind you, below directly in front or below your wing? Herewith the most recent (as of this post) fatal accident in the NTSB database involving a Diamond: https://app.ntsb.gov/pdfgenerator/Repor ... L&IType=FA
- Do you really scan outside 180 degrees left and right? I recently had a fairly close call with an aircraft approaching from the right at about an 80 degree angle off to the right of my heading. My strobes (or anything else) didn't seem to cause him to take any action. He was ADS-B out, and one would presume he was ADS-B in, but may not have been paying attention to it.
- Traditional reliance solely on eyeballs and radio transmission just doesn't cut it. We all know this to be true. We actually have a problem in this area with lots of foreign students with little command of the English language operating in the pattern. A very high percentage of their transmissions are unintelligible. When I can't pick them out visually (which is most of the time) I use FF display to discern what they're doing and where to look for them. Fortunately the flight school they're using has equipped their entire fleet with 1090ES. We also have a problem with frequency saturation here, with lots of transmissions being stepped on.
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Re: Musings on traffic detection

Postby RMarkSampson » Thu Aug 09, 2018 1:16 am

Unfortunately that accident was the result of bad timing, unfortunate geometry, approach speed differences and poor comms prep (old CTAF freq) - it took all those factors to line up for that midair to happen. In this case it was two low wing aircraft that were lined up on the same heading. Even more prevalent than that scenario, a low wing aircraft above a high wing aircraft has at least a 180 arc of "can't see you" danger to it. Plenty of times my ADS-B has alerted me to traffic where I dipped my wing to see the lower altitude traffic - and also realized that there was zero chance of that pilot seeing me because I was looking at his high wing vice his canopy.

Per your incident you mention, the audio call out feature of my GDL-84 is money well spent. All my traffic is via Bluetooth to my iStuff running ForeFlight. My iPad is in a good visual position but it is still a few feet across the cockpit. I also suction cup my iPhone 8+ on the canopy so it is less than a foot away when glancing down. With these electronic devices working for me, I still sometimes get first notified of traffic from an aural traffic call into my headset from the GDL-84.

Assuming I have a passenger I call my ADS-B my third set of eyes. When you talking and listening on CTAF, have ADS-B traffic at a glance in the cockpit, audio callouts from your ADS-B, good 'ol Flight Following - and still maintain an effective visual scan, you have then totally stacked the deck in your favor. If just looking outside is your only defense - I hope you fly in an unpopulated airspace. As I see more and more tail numbers showing up on my iPad in Foreflight I know we both have ADS-B and our planes are talking to each other. We don't even need a radar environment and/or a ground station to pass data packets - that is a comforting thought. Accident wise, midair collisions are a fairly low occurrence. As more and more of us gear up with ADS-B, the probability will never be zero, but I will certainly muse less and less on the potential for a midair.
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Re: Musings on traffic detection

Postby Lou » Thu Aug 09, 2018 1:39 am

I have always said that the risk of a midair collision is a lot lower than a mid-road one overall. But on the way back from Oshkosh, in the middle of the empty southern Canadian prairie, while being watched on flight following, I was alerted by the Avidyne TAS: "traffic 1 o'clock less than one mile." I scanned, and picked up an RV crossing my path right to left at exactly my altitude. It was easy to disconnect the AP, turn right and let him pass. I could see him clearly - I don't think he ever saw me. Why flight following did not alert me, who knows. It would have been a startling surprise and likely a near thing without the TAS warning.

A few years back there was an en route air to air in central Saskatchewan - what are the odds?

I would not trade my TAS for a Mark I eyeball for anything. I wish Diamond DA40 owners had more economical ADS-B solutions but for peace of mind and situational awareness it is still worth it.
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Re: Musings on traffic detection

Postby pietromarx » Thu Aug 09, 2018 3:31 am

I just flew LA-Wyoming-St Paul-Pittsburgh and tomorrow on to NY. I've had flight-following the entire way, but this is the first time I've taken the ADS-B unit across the country. With both Avidyne TAS and Garmin ADS-B it is interesting seeing all of the targets near airports and how few anywhere enroute. For traffic avoidance over the years I've had eyeballs, flight-following, IFR control, TIS, TAS, and now ADS-B. Only the last one has given me any sense of security. The amount of traffic in LA, SF, and NY is truly impressive (often more than 90 unrestricted targets simultaneously).

On a side note, I have seen very few GA aircraft this trip. Only one Cirrus. No Diamonds. Where is everyone?
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Re: Musings on traffic detection

Postby RMarkSampson » Thu Aug 09, 2018 9:41 am

Musing on the computer which is not as good as flying but the fuel burn is measured in BPH (beers per hour).

I just reread my post - did I really just say “...gear up...”. From a DA-20 gear down and welded guy, my apologies to all you DA-42/62 fliers out there. May your gear forever swing in the wind...
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Re: Musings on traffic detection

Postby Sandy » Thu Aug 09, 2018 10:42 am

After having flown for over 45 years, I still say that the only thing that scares me about flying is that other people do it.

My GTX345R is being installed next week.

Sandy
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Re: Musings on traffic detection

Postby Tim H » Thu Aug 09, 2018 12:35 pm

My initial reaction after installing ADS-B was “WOW - I feel so much safer now that I can see all these other airplanes out there”.

After I couple of months of flying with ADS-B, I better appreciate its limitations.

One, it does not show EVERY airplane out there, I’ve seen many airplanes with my eyes that DID NOT show up on ADS-B (at altitudes that should be covered by radar).

Also, just because you see an airplane on ADS-B with a tail number, it does not mean they have ADS-B IN. So, don’t assume they see you just because you see their tail number.
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Re: Musings on traffic detection

Postby Rich » Thu Aug 09, 2018 1:49 pm

The limitations of ADS-B are well known. For example, folks fly around with transponders off (or standby or don't have one or ...). Even though they may be in range of some radar system you won't see them through TIS-B, as primary (i.e. passive) targets are not fed through the TIS-B system. So out the window is your only option for these aircraft. Some areas of the country are more prone to this behavior than others.

As for being ADS-B out and not in, that's a real possibility. Especially when multiple people use the same plane, for example flight schools. For a short time after I equipped for ADS-B out, other guys flew my plane and it was up to them whether they were -in equipped.
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Re: Musings on traffic detection

Postby Colin » Thu Aug 09, 2018 2:59 pm

Just landed KOWD (Norwood) yesterday. In the summer haze I watched a Cessna cross less than 500 feet below me, 90 degrees to my path of flight, less than a mile ahead of me. The controller called it out, the G1000 called it out, ForeFlight called it out... and I am sure the Cessna was oblivious that I was there at all. The controller was *much* happier when I said I had the guy in sight. I had his N number and everything.
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Re: Musings on traffic detection

Postby RMarkSampson » Thu Aug 09, 2018 4:06 pm

Only ADS-B Out will be the requirement- and some airspace is exempt. I’ve had conversations with those who only intend to comply with the minimum which means not getting an ADS-B In solution. I also remember a conversation between a tower and someone arriving who did not have a transponder installed - and the airport was inside a Mode-C ring. Thought that required a special permit but alas no one seemed to raise the issue...

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