ADSB out creating more risk until 2020

Discussion in 'Lessons Learned' started by Salty, Apr 17, 2017.

  1. citizen5000

    citizen5000 Pre-takeoff checklist

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    The current Cirrus Perspective ADS-B setup has audibles with non threat, proximity advisory's and threat advisory's. Proximity advisory's display a solid white diamond/triangle when an aircraft is +- 1200 feet and within 6nm. Threat advisory's are solid yellow diamond/triangle and warn according to a TA configurable closing rate, distance and vertical separation. All other targets are open diamond/triangle and do not produce an audible warning.
     
  2. citizen5000

    citizen5000 Pre-takeoff checklist

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    Plane to plane ADS-B target warning is real time. Ground station data takes microseconds longer. Nexrad (free) and XM weather have similar delays (anywhere from 5 to 10min). Most of that delay is drawing the screen from the data. On board weather radar is superior of course but you also pay tons to get it and you usually only find it on multi-million buck aircraft.
     
  3. jsstevens

    jsstevens En-Route PoA Supporter

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    Plane to plane ADS-B is a least 1 second (if that seems real-time to you I understand, but I've working in environments where double digit millisecond latencies are too slow, so real-time means something different to me) and may be more depending on traffic amount and other system functions. The real issue is GPS which is feeding the position data (and, I presume, the velocity data) in the ADS-B outputs are not always accurate. Are they accurate (within a few meters) most of the time? Yes. But it only takes once...

    And yes, the anti collision radar, or even weather radar, on-board is cost prohibitive for most of the small GA fleet. I've never piloted a plane with either one. Maybe someday...

    John
     
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  4. ChiefPilot

    ChiefPilot Pre-Flight

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    I've observed delays of significantly longer, and had the actual traffic in sight. I believe the system actually allows several (up to six comes to mind, but I don't recall which doc that was from) seconds of delay for TIS-R, but what I've observed is that it can be longer than that in some situations.
     
  5. exncsurfer

    exncsurfer Cleared for Takeoff

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    I think that radar delay you describe is also a problem for ATC as well. They are limited by the sweep interval, not sure how long that is, but if its a fast moving target close to you, it could mean a lot. That was the radar vs ads-b comparison I was referring to in a previous post.(not on-board radar).

    Would you be able to differentiate the targets in the data? Like could you have your alert append the word: radar, blah blah blah, that might help.
     
  6. citizen5000

    citizen5000 Pre-takeoff checklist

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    The FAR for ADS-B is 14-CFR 91.227: https://www.law.cornell.edu/cfr/text/14/91.227

    (e)ADS-B Latency Requirements -

    (1) The aircraft must transmit its geometric position no later than 2.0 seconds from the time of measurement of the position to the time of transmission.

    (2) Within the 2.0 total latency allocation, a maximum of 0.6 seconds can be uncompensated latency. The aircraft must compensate for any latency above 0.6 seconds up to the maximum 2.0 seconds total by extrapolating the geometric position to the time of message transmission.

    (3) The aircraft must transmit its position and velocity at least once per second while airborne or while moving on the airport surface.

    (4) The aircraft must transmit its position at least once every 5 seconds while stationary on the airport surface.

    ADS-B ground stations broadcast up to 100 to 250 miles in range. Targets can be seen up to 20nm out and thousands of feet above and below. There are three levels of notification: 1. planes not in proximity, no audible. 2. planes in proximity +-1200 feet, 6nm or closer, audible 3. threats configured by speed, distance and altitude, audible/colored.

    Radar latency is longer than ADS-B and add to that a human reading the screen and making a radio call for traffic advisories.
     
  7. jsstevens

    jsstevens En-Route PoA Supporter

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    And this is the requirements for transmission. What are the requirements for reception? And if you are in a high traffic area, how many of these transmissions can you receive at the same time? The actual radio signals can step on each other. I also assume (its not in the requirements above) there is some means for varying the timing so you don't have a couple of airplanes whose transmissions are synced to the second and therefore step on each other repeatedly.

    Please don't misunderstand me: I think ADS-B is a great advancement for many of the reasons it was introduced. Better information where there is no radar coverage, better information between aircraft, cheaper weather in the planes (although XM isn't expensive). But it's not magic, and like all tech it has limitations. Understand them so you know when to be suspicious.

    John
     
  8. exncsurfer

    exncsurfer Cleared for Takeoff

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    I suspect the receiving ability is better than what you suspect. :) I've been trying to find a number, like how many aircraft per station can it handle, haven't found that but I found a ground station flyer(i guess) that claims is decodes 99% of the messages. It is able to differentiate overlapping signals based on variances in the signal strengths received. At any rate, it will probably only increase in accuracy going forward. http://usa.selex-comms.com/internet/localization/IPC/media/docs/1090_Ground_Station_EN_LR.pdf
     
  9. jsstevens

    jsstevens En-Route PoA Supporter

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    What can the receiver in the plane handle?
     
  10. exncsurfer

    exncsurfer Cleared for Takeoff

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    Not sure, I would think it would have much less to process as its sensitivity isn't going to have the range of the ground station. Also, any targets it doesn't receive the ground station will provide(and I assume would provide in a consolidated broadcast not requiring any or much processing). I'm not sure how it merges the two, but I assume it does.

    Good question though, I have no idea. :)
     
  11. Salty

    Salty Pre-takeoff checklist

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    Where do you get this stuff? Maybe you should actually re-read my OP. I've "reasoned" no such thing.
     
  12. citizen5000

    citizen5000 Pre-takeoff checklist

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    From your text.

    citizen5000 said:
    It is a completely false premise that TCAS and/or ADS-B stops/hinders outside cockpit scans. In fact, the tech makes the scans more focused and efficient.

    Salty reply: I respectfully disagree. Human nature says otherwise.
     
  13. denverpilot

    denverpilot Taxi to Parking

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    None of which accounts for missed transmissions or the standard collision problems of a "hidden node" RF system.

    FAA isn't publishing those stats. But as a layman RF engineer I can tell you this, you can transmit every second of your life on the ground at KAPA and the tower to the southeast over the ridgeline will never ever hear it at frequencies at or above 978 MHz.

    Other aircraft will hear it DIRECT if... their antenna isn't physically blocked by the fuselages, the buildings, the hills, and isn't reflected by anything in the environment, and they're not clobbered by other aircraft's transmissions.

    One can know the preamble, data, and post transmission delays for T/R switching (not big but usually measurable) on all the devices participating and calculate a maximum number of users in any particular coverage area. One of the ADS-B engineers here did the math for all of us a couple years ago, and it showed clearly why Mode-S couldn't be relied upon solely in terminal areas. Too many aircraft.

    The above also doesn't factor in any time for reception, sending to a post-processor to remove bogus data, the processing time of that filter, and transmission back to the uplink site.

    Some of that is in the spec which can only be obtained by pay-to-play, even though it's a system owned by the public. And there's a lot of it that simply isn't available. Only the contractor who built the stuff knows the specs. Se-cur-I-tah, and all that rot.
     
  14. JimNtexas

    JimNtexas Pattern Altitude

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    Since you know the other pilot, what did he say when you asked him for his side of the story?
     
  15. Salty

    Salty Pre-takeoff checklist

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    Nothing I said indicates that I know the other pilot. But obviously you are reading into my words something that isn't there, so out with it.
     
  16. CC268

    CC268 Cleared for Takeoff

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    Maybe I'm misunderstanding but you'd rather use paper charts than ForeFlight, etc? Or your just saying you won't use ForeFlight as a traffic advisor (assuming you have a Stratus or whatever)?
     
  17. Ravioli

    Ravioli Pattern Altitude PoA Supporter

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    Paper for me. No tablets.
     
  18. citizen5000

    citizen5000 Pre-takeoff checklist

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    AvWeb: ADS-B Rebate Requests Stall http://www.avweb.com/avwebflash/news/ADS-B-Rebate-Requests-Stall-228873-1.html

    Just 5,008 reservations for rebates have been made and 14,910 rebates remain to be claimed by the end of the program on Sept. 18, 2017.

    The “fly and validate” phase has 3,707 participants, 3,620 have filed a claim, and 1,064 reservations expired.

    The lack of interest may result in tens-of-thousands of planes failing to get upgraded by the 2020 mandate. This will mean none of these planes will be able to fly in controlled airspace, B or C, and above 10k feet msl in Class E. And none will be able to fly in the flight levels.
     
  19. denverpilot

    denverpilot Taxi to Parking

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    Or people are like... "$500 doesn't even move the needle on a ridiculous $5000 install for something nobody actually needs."

    And are waiting to see if there's anything else coming down the mother-may-I? certified avionics crack pipe.
     
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  20. Ravioli

    Ravioli Pattern Altitude PoA Supporter

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    We finished the PA32-300 and the check is in the mail. Oddly, we are NOT eligible for the C177RG because it's one per owner, not one per tail number.

    And as I said earlier, I'm waiting till the last minute for the RV-6A so I can capitalize on someones upgrade or whatever cool new stuff turns up at Osh.
     
  21. denverpilot

    denverpilot Taxi to Parking

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    Oh I'd have sooooo set up a second LLC for that crap. 5 minutes online and $20 to the State, to get $500 back from the Feds? Definitely. LOL.
     
  22. Ravioli

    Ravioli Pattern Altitude PoA Supporter

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    One LLC owns the two planes and another LLC owns mine.

    But... your idea is not unusual. Many operations have one LLC per tail to segregate the liability. I don't know if that actually works or if it gets pierced. Not my specialty.

    The dumb rebate to help with the dumb mandate probably assumed if you have more than one plane you didn't need the assist.
     
  23. denverpilot

    denverpilot Taxi to Parking

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    Yeah it probably gets pierced as far as liability goes, but for the case of this paperwork it's still two owners.

    I don't own my airplane. The LLC owns it. I own 50% of the LLC. The LLC also owns a nice tug and some other stuff. I'm jealous of my LLC. :)
     
  24. Velocity173

    Velocity173 Final Approach PoA Supporter

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    Radar sweep is anywhere from 4.7 secs (terminal) to 12 secs (ARTCC). That's old school single sensor though. More and more facilities are going FUSION with multiple radar feeds providing a tracked target with a decreased delay. The farther you are away from a single source radar, the less accurate the position the target becomes as well. FUSION (including ADS-B) provides for a more precise target position and doesn't require the old increased separation beyond a certain distance (40 miles).
     
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  25. Matt Brasher

    Matt Brasher Filing Flight Plan

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    The only "human nature" I need to know is that no one can scan the entire sky for traffic -twice- per second. That's up to 24 times the refresh rate of radar, and that doesn't include the 3-4 second radio call required to relay that 12 second old information provided by FF.

    No one is calling it a replacement for see-and-avoid. What they are calling it is a huge aid in identifying traffic locations.
     
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  26. citizen5000

    citizen5000 Pre-takeoff checklist

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    Correct. ADS-B "in" is another aid in situational awareness with added bonuses (FIS-B).

    Flying Magazine has a similar debate going on. I am guessing the naysayers are guys that don't have the tech and don't want to upgrade. They "imagine" scenarios that justify not upgrading and irrationally cling to them. Those that have the tech are flying safer and with more confidence.
     
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  27. denverpilot

    denverpilot Taxi to Parking

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    There's all sorts of tech out there that isn't worth paying too much for. ADS-B is somewhere in the middle. It has significant problems but also has significant benefits once in a while.

    Many are also annoyed with the fake marketing around mandating it. It's never a good idea to lie to a customer about the benefits of a product, nor treat a customer like an idiot.
     
  28. Salty

    Salty Pre-takeoff checklist

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    I recommend actually reading my OP.
     
  29. JimNtexas

    JimNtexas Pattern Altitude

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    What I'm reading is this:

    "The other pilot had ADSB out and I do not."

    If you don't know the other pilot, and you don't have ads-b, then how do you know what equipment the other pilot had?

    Also, if you want audible warnings with bearing, altitude, and distance the Garmin 345 transponder with a GTN-650 provides that feature.
     
  30. Salty

    Salty Pre-takeoff checklist

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    I know I don't have adsb out. I got alerted about him via adsb-in with no ground station connection. Based on my understanding that means he had adsb out. Feel free to correct my logic if it is wrong.
     
  31. exncsurfer

    exncsurfer Cleared for Takeoff

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    I'm curious how do you know there was no ground station connection. I've never used in or out, do the targets look different if they're provided air to air vs ground station to air? If not, any adsb-out in a 150 mile radius could have triggered your receiver to receive targets provided by the ground station, which could be coming from ATC radar if he is assigned a squawk code, right?
     
  32. citizen5000

    citizen5000 Pre-takeoff checklist

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    You are missing the point. ADS-B is a MANDATE. It's not buying new seat covers on Amazon. ADS-B works exactly as advertised there are no problems.

    Like I said those who are not flying with the tech by now likely resent having to make the upgrade. They seem to want to fight it to the last minute.
     
    Last edited: Apr 25, 2017 at 1:16 PM
  33. dmspilot

    dmspilot Pattern Altitude

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    No it isn't.
     
  34. Salty

    Salty Pre-takeoff checklist

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    There was a big red X over the ground station symbol.

    Honestly, maybe you are right, maybe I got the alert from an airliner at Fl350 about him based on a radar contact. I didn't think it worked that way, but maybe I'm wrong. I know the closest towered airports dont have radar, but maybe the class bravo 50 miles away could pick him up, relay it to an airliner and then on to me. I don't think so, but I don't know. Maybe that's why I didn't get the alert until he was < a mile away.
     
  35. exncsurfer

    exncsurfer Cleared for Takeoff

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    Yea, you're probably right then, I'm not sure but I don't think the airliner would relay other traffic to you as a ground station would.
     
  36. denverpilot

    denverpilot Taxi to Parking

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    Anyone who waited until now got about a $3000 discount off of the originally listed prices (competition) and a socialist style rebate from FAA of $500.

    Saving $3500 doesn't seem all that unintelligent considering it's pretty typical to see prices fall toward the final years before any government mandate.

    No point in buying a Lynx now at $8000 when Garmin just matched Stratus' price and added GPS on the 335.

    If your little toys are broken until the mandate date, why should anyone else care? The mandate date is when it has to be done, not sooner.

    Do you work for someone who's getting their ass kicked by Garmin and hoping to make a few more quick sales? LOL.

    Garmin has more money to throw at it if they want to.

    Save themselves some inventory management and drop the 335 and just make the 345 standard, perhaps. No point in maintaining both, although it's probably the same hardware with a daughter board slapped in. But why bother stocking both? More inventory is usually not worth it in those cases.

    They're obviously having fun toying with Stratus though.

    And Aspen. The G5 just killed that.
     
  37. Clark1961

    Clark1961 Touchdown! Greaser!

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    When ADS-B is received directly from an aircraft more info is available.
     
  38. citizen5000

    citizen5000 Pre-takeoff checklist

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  39. dmspilot

    dmspilot Pattern Altitude

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  40. JimNtexas

    JimNtexas Pattern Altitude

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    Thanks, that explains what happened. Your ADS-B in could see him, but since you were out of tower range and didn't have ads-b out the other pilot could not see you on his ADS-B display.

    That's by design, and why ADS-B makes no sense without the mandate.