Foreflight ground traffic bug

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Rich
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Foreflight ground traffic bug

Post by Rich »

The documented behavior is that when an ADS-B equipped aircraft has transitioned to ground mode, FF continues to track it and displays the triangle/diamond in kind of a brown color. This used to work fine, but in recent years I noticed it was no longer doing this. The target symbol simply disappears. I'll skip the back-and-forth with FF support, but they asked me to turn on logging and try to duplicate the problem. So today, here's what I found, running tests at Redmond (KRDM) and Bend (KBDN):

Important distinction: There is an ADS-B tower right at BDN. No tower reception available on the surface at RDM. I suspect this is a relevant factor.

1. Ground traffic symbols seem to work perfectly at BDN. I saw lots of these.
2. Ground traffic symbols are not displayed at RDM. Plane inflight symbols (green) would suddenly appear right at takeoff and disappear upon landing.
3. I watched 2 aircraft (N62GG, 404QX) land, with the data bubble displayed as they did. The green symbols disappeared, no brown symbols were displayed but in the data bubble for both of them the notation "(SFC)" appeared. This tells me they were properly being detected as ground traffic but FF failed to display the expected graphic symbol. Though there was no graphic symbol the data bubble remained for each case and tracked their speed and path as they taxied.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Rich
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Re: Foreflight ground traffic bug

Post by Rich »

FF support so far claims to not be able to repeat this problem and essentially asked for proof with screen shots. So here they are. Aircraft just coming in and a few seconds later. In the second the symbol has disappeared altogether but the data bubble (if you had already brought it up) tracks the now invisible target. You need to select these pictures to enlarge them to see the difference.
N52371-appch.jpg
N52371-SFC.jpg
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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chili4way
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Re: Foreflight ground traffic bug

Post by chili4way »

The "no towers" in the upper left corner suggests that the traffic may be coming from the FlightAware feed over an internet connection and not ADS-B. If that's the case, then the transition from "flight" to "ground" representation might be up to FlightAware and not Foreflight. I'll be interested in seeing how FF replies. Thanks for sharing this with the DAN folks.
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Rich
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Re: Foreflight ground traffic bug

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chili4way wrote: Wed Jan 20, 2021 3:02 pm The "no towers" in the upper left corner suggests that the traffic may be coming from the FlightAware feed over an internet connection and not ADS-B. If that's the case, then the transition from "flight" to "ground" representation might be up to FlightAware and not Foreflight. I'll be interested in seeing how FF replies. Thanks for sharing this with the DAN folks.
No, it can only be ADS-B. My iPad has no cellular capability and its Wifi connection is Stratus only, which has no internet capability. Also, if you look at the data bubble it clearly shows 1090 ADS-B. Flight Aware data bubbles say Flight Aware and are different in several other ways.

There's some evidence that this change in behavior is related to the use of Stratus 3. This used to work and I used to use a Stratus 2. And the way the technician failed to reproduce the problem was with use of a Sentry. Stratus 3 also introduced availability of a communication protocol that is not FF specific. This difference in software may have broken some bit of the FF/Stratus integration.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Steve
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Re: Foreflight ground traffic bug

Post by Steve »

I have not seen this behavior on mine, but my system is different - I use a Scout ADS-B receiver. Plus my home airport is not particularly close to any towers, and typically, aircraft do not show up at all until about 3-400 feet AGL in this area. I will have to pay more attention when I fly close to KSAT or KRND, which have towers closer to the airport.
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Rich
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Re: Foreflight ground traffic bug

Post by Rich »

Getting these screenshots required some patience. I needed to capture an ADS-B aircraft that would approach and land. The typical ADS-B out device will stay in non-ground mode during this activity.

For some reason, traffic was way down at KRDM and what little activity there was consisted of all take-offs or touch and goes, except for one non ADS-B cub that is, of course, invisible to the Stratus. And then there is that Stratus setting that I forgot that shuts it down after a period of non-movement when running on battery. Altogether I sat there for 45 minutes before I caught something. Kind of like fishing (appropriate, since these gizmos are often referred to as fish-finders :D )
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Rich
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Re: Foreflight ground traffic bug

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Steve wrote: Wed Jan 20, 2021 4:35 pm I have not seen this behavior on mine, but my system is different - I use a Scout ADS-B receiver. Plus my home airport is not particularly close to any towers, and typically, aircraft do not show up at all until about 3-400 feet AGL in this area. I will have to pay more attention when I fly close to KSAT or KRND, which have towers closer to the airport.
This is confusing. Are you saying you don't see anything until 3-400 ft but you still see them in ground mode?
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Steve
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Re: Foreflight ground traffic bug

Post by Steve »

Rich wrote: Wed Jan 20, 2021 4:39 pm
Steve wrote: Wed Jan 20, 2021 4:35 pm I have not seen this behavior on mine, but my system is different - I use a Scout ADS-B receiver. Plus my home airport is not particularly close to any towers, and typically, aircraft do not show up at all until about 3-400 feet AGL in this area. I will have to pay more attention when I fly close to KSAT or KRND, which have towers closer to the airport.
This is confusing. Are you saying you don't see anything until 3-400 ft but you still see them in ground mode?
Nope. I don't see any traffic at all till they climb past 3-400 feet on takeoff, and lose the target completely when they descend below approximately that altitude. This occurs whether I am on the ground, or in flight. I can see airborne targets (above that altitude threshold) when I am on the ground, but not AOGs taxiing on my airfield.
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Rich
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Re: Foreflight ground traffic bug

Post by Rich »

Steve wrote: Wed Jan 20, 2021 4:50 pm
Rich wrote: Wed Jan 20, 2021 4:39 pm
Steve wrote: Wed Jan 20, 2021 4:35 pm I have not seen this behavior on mine, but my system is different - I use a Scout ADS-B receiver. Plus my home airport is not particularly close to any towers, and typically, aircraft do not show up at all until about 3-400 feet AGL in this area. I will have to pay more attention when I fly close to KSAT or KRND, which have towers closer to the airport.
This is confusing. Are you saying you don't see anything until 3-400 ft but you still see them in ground mode?
Nope. I don't see any traffic at all till they climb past 3-400 feet on takeoff, and lose the target completely when they descend below approximately that altitude. This occurs whether I am on the ground, or in flight. I can see airborne targets (above that altitude threshold) when I am on the ground, but not AOGs taxiing on my airfield.
So you're somewhat similar to my experience, except I will see any traffic that is in non-ground mode, even when on the ground. Most ADS-B out GA planes make this transition based on airspeed or ground speed. I have heard of some that include an initial altitude change to switch, which is what you may be seeing. Others use an actual squat switch. As I observe a touch and go the usual case is the in-air mode stays on all the time and the target remains visible because the plane never gets below the target air/ground speed. On a normal takeoff the target appears during the takeoff roll.

Otherwise it looks like you're having the same behavior with respect to ground mode that I'm seeing.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Steve
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Re: Foreflight ground traffic bug

Post by Steve »

Could be. No one does touch and goes at my home field - it is too short and has a hill at one end.
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