instrument malfunction (ADS-B)

[Unregistered]

Has anyone experienced significant issues with their situational awareness instruments while in flight? If so, how did you deal with it?

In particular, I’m most interested in experiences with ADS-B and situations where the ADS-B display seemed to differ from reality. For example, the ADS-B display showed

other a/c ahead, but according to the tower or you own eyes (under clear conditions) there wasn’t any traffic.

 

[Marauder]

I have the Garmin Pilot app running the GDL-39. Since I don't have an "out" solution for ADS-B, the majority of what I see is the 1090 crowd. I do sometimes get FIS-B when an "out" airplane is near me broadcasting the 978. In all cases, the traffic is where it says it is.




Sent from my iPad using Tapatalk

 

[Norman]

Has anyone experienced significant issues with their situational awareness instruments while in flight? If so, how did you deal with it?

In particular, I’m most interested in experiences with ADS-B and situations where the ADS-B display seemed to differ from reality. For example, the ADS-B display showed

other a/c ahead, but according to the tower or you own eyes (under clear conditions) there wasn’t any traffic.

Why did you post anonymously? Fishing?

 

[Marauder]

Why did you post anonymously? Fishing?

Scared, very scared...

 

[JHW]

we used to have one antonov with a display that would sporadically show us at a particular location east of Moscow before returning to our actual location in southern africa. Sometimes it would get stuck in that mode and the only way to get it out was to key a next waypoint in russia into the FMS, then it would realize the error of its ways and go back to normal.

what's the point of this exercise ?

 

[Jim_R]

I've had my ADSB device indicate traffic that I couldn't see, just like I've had ATC call traffic to me that I never saw, even in clear conditions.

Not sure how that's a "significant issue" or "differ[ent] from reality".

 

[wsuffa]

TIS will sometimes show a radar return that is my own plane. Depends on location and facility... And, I assume, processing delay.

 

[deeruck]

TIS will sometimes show a radar return that is my own plane. Depends on location and facility... And, I assume, processing delay.

I always get that call when climbing out, about 500ft AGL in the club's 172SP.

 

[slavinger]

TIS will sometimes show a radar return that is my own plane. Depends on location and facility... And, I assume, processing delay.

Yep, when doing steep turns in a TIS equipped a/c it's not uncommon to get a traffic alert on yourself. And I've also spotted traffic nearby that TIS and ATC never alerted me to... Maybe txponder was off?

 

[flyingron]

I think the TIS issue especially happens on areas of radar mosaic piece overlaps. There's a place between CJR and OKV where m TIS shadow always appears. I suspect something in the computer isn't quite aligned properly.

Of course, there are TWO different things with ADSB-B. The autonomous part (which we're not there yet because very few people are so equipped) which is roughly on a par with TCAS and the broadcast traffic service.

Of course, the biggest issue is NOT the stuff that shows up on the traffic display that isn't there, it's the stuff that doesn't show up on the traffic display that IS there.

 

[JOhnH]

Why did you post anonymously? Fishing?

Perhaps he was flying over max gross weight with two student pilots at the controls and a tank of propane in the back!

My Stratus II doesn't show everything because I don't have "out". But any time it showed something nearby, it was right about where the stratus said it was. I was going to sell my Zaon when I got the stratus, but I found that it will often pick up planes nearby that the Stratus doesn't.

 

[azure]

Of course, there are TWO different things with ADSB-B. The autonomous part (which we're not there yet because very few people are so equipped) which is roughly on a par with TCAS and the broadcast traffic service.

I've always been curious about this phenomenon (ownship called out as traffic). I have a GDL-90 which overlays traffic on a GMX-200. This happens VERY frequently and there is no pattern as to where it happens, geographically. It's annoying, since a not negligible fraction of the GMX-200 moving map display is covered up by the traffic alert box (plus I have the distraction of hearing Bitchin' Betty calling out "traffic, traffic!).

Of course, the biggest issue is NOT the stuff that shows up on the traffic display that isn't there, it's the stuff that doesn't show up on the traffic display that IS there.

Agreed. The traffic display can give you a false sense of security if you trust it to show you everything. All too often ATC calls out traffic to me that does not show up on my display. It's not just the x-ponderless folks either -- sometimes they call out an altitude, and I still see nothing on the display.

 

[Clark1961]

Agreed. The traffic display can give you a false sense of security if you trust it to show you everything. All too often ATC calls out traffic to me that does not show up on my display. It's not just the x-ponderless folks either -- sometimes they call out an altitude, and I still see nothing on the display.

Are these non-displayed targets generally at lower altitudes?

My passive traffic sensor does pretty good with traffic at higher altitudes...and of course the ADS-B traffic is pretty good around the DEN Bravo...

 

[John Collins]

I've always been curious about this phenomenon (ownship called out as traffic). I have a GDL-90 which overlays traffic on a GMX-200. This happens VERY frequently and there is no pattern as to where it happens, geographically. It's annoying, since a not negligible fraction of the GMX-200 moving map display is covered up by the traffic alert box (plus I have the distraction of hearing Bitchin' Betty calling out "traffic, traffic!).


Agreed. The traffic display can give you a false sense of security if you trust it to show you everything. All too often ATC calls out traffic to me that does not show up on my display. It's not just the x-ponderless folks either -- sometimes they call out an altitude, and I still see nothing on the display.

Can you distinguish when you are receiving the TISB service from when you aren't with the GDL90/GMX200? The GBT transmits a list of client Aircraft ID's that are receiving the TISB service. As an aircraft approaches the limits of the TISB service area for the GBT, the Aircraft ID is still sent, but with a bit indicating that service is no longer being provided. In theory, an indication of this should be displayed somewhere so the pilot knows when the traffic picture may be incomplete. There is a 20 second timeout in the UAT if it hasn't received its Aircraft ID with the TISB bit on. I am not sure if this capability exists on the GDL90 or not.

 

[azure]

Can you distinguish when you are receiving the TISB service from when you aren't with the GDL90/GMX200? The GBT transmits a list of client Aircraft ID's that are receiving the TISB service. As an aircraft approaches the limits of the TISB service area for the GBT, the Aircraft ID is still sent, but with a bit indicating that service is no longer being provided. In theory, an indication of this should be displayed somewhere so the pilot knows when the traffic picture may be incomplete. There is a 20 second timeout in the UAT if it hasn't received its Aircraft ID with the TISB bit on. I am not sure if this capability exists on the GDL90 or not.

I'm not sure, either. I haven't looked through my (very limited) GDL-90 documentation in a long time. I've always assumed that if I was out of range of the GBT, I would see no traffic at all, not an incomplete traffic picture. That's an interesting possibility, though ISTR that this has happened not far from home base too, which is smack dab in the middle of the local TIS-B service area.

And no, I believe it can happen at any altitude, and the unseen targets aren't always low-lying either.

 

[John Collins]

TISB service volumes are not made available to the public and may be different than line of sight. Within a service volume, if you approach the lateral or vertical boundaries of the service volume, you may cease to have TISB as a service. Your hockey puck based on your altitude +/- 3500 feet and 15 NM around you is where you expect to receive TISB, but if you are towards the top, bottom, or edge of a service volume, at some point the TISB information may not be available, at least for traffic outside the GBT service volume but within your hockey puck. Knowing when you are within the GBT service volume and receiving the TISB service is important information for the pilot.

I used to get the refrain from engineers who worked for me when there was silence on the support line: "No News is Good News". I was more of a pessimist and would answer back "No News is No News".

 

[winrose46]

I have the GDL-88 installed and in the more than 15 hours of flight with it, I have seen about 30% of the displayed traffic. This is similar to ATC traffic advisories I have received on IFR trips. Note that my iPad display agreed every time with ATC. See and avoid seems to work for the last 20 seconds. The iPad (with Wing X and traffic) puts yellow circles around your aircraft and potential conflicting aircraft.

 

[barelyawake]

Stratus II/ForeFlight ADS-B Issues:

- May receive traffic information from ground station that has been activated by a passing aircraft equipped with ADS-B "out".
- May receive traffic information relayed from ground station through another aircraft equipped with ADS-B "out".

When receiving relayed traffic information from another aircraft, FF may show an echo of your own aircraft. Appears suddenly, usually within 200 ft altitude and 1/4 mile from your position. Position differences are due to different altitude interpretations between systems (Stratus/other aircraft equipment) and transmission time delay.

FF released an update a couple months back to address the issue, however as recently as last weekend the "echo" still occasionally appears.

If it first happens to you on your very first night X-C I would suggest that a 360 to clear your tail and a call the local center to verify traffic will help to calm your nerves. And provide impetus to research the issue when you're on the ground. That's just a guess . . .

YMMV