Any operational benefits from ADS-B out yet?

[John Collins]

The ADS-B TISB traffic system is a broadcast based system. No aircraft is assured of receiving any particular broadcast. In the case of ADS-B positions, the broadcasts are once per second. TISB can be as slow as once every radar sweep past the aircraft which can be 5 seconds for a single terminal radar and a dozen seconds for enroute. Usually there are multiple radars providing target information for a given target, so the repetition rate is usually faster. TISB is not intended to be anything other than an aid to visual acquisition, it is not TCAS or TAS of any sort. TISB is a carrot and not essential to the purpose that the system is intended to provide, which is surveillance. Outside of the US, there is no TISB service. The data being broadcast has a short lifespan (a few seconds) before it is out of date and missing a TISB now and then is not an issue.

A paraphrase of RTCA DO 317A defines that the "in service" message is to be broadcast sufficient number of times by a ground station so that within a 20 second period there is a 95% chance of it being received. The repetition rate is not stated. UAT can package up to 100 ICAO aircraft ID's into a single broadcast. If no "in service" message is received within 40 seconds, then the "in service" indication should be turned off. IOW this is just used to inform the pilot that they are receiving or not receiving the TISB service.

Anyone using a portable ADS-B system for assistance with traffic acquisition should be aware of the system's limitations and its dependence on having both a good GPS position and a clear view to the ground station, meaning external antennas. It works as an aid to locate most traffic, but not all and you must stay diligent with see and avoid as it is not an equivalent to an active traffic system or to TCAS.

 

[dans2992]

It's just an "advisory" system, so they designed it "as best they could" and left it at that.

The big iron (big money) guys get their traffic info elsewhere. I.e. TCAS, etc.


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[denverpilot]

Anyone using a portable ADS-B system for assistance with traffic acquisition should be aware of the system's limitations and its dependence on having both a good GPS position and a clear view to the ground station, meaning external antennas. It works as an aid to locate most traffic, but not all and you must stay diligent with see and avoid as it is not an equivalent to an active traffic system or to TCAS.

This seems to be where the marketing doesn't meet the meat.

We're only five years out from virtually nobody using a portable if the regulatory mandates hold into 2020, correct?

Is it your opinion the installed non-portables don't have these flaws?

It's just an "advisory" system, so they designed it "as best they could" and left it at that.

The big iron (big money) guys get their traffic info elsewhere. I.e. TCAS, etc.

Billions spent for an "advisory only" system with some pretty significant data transport flaws. Not a great value overall.

 

[NoHeat]

Anyone using a portable ADS-B system for assistance with traffic acquisition should be aware of the system's limitations and its dependence on having both a good GPS position and a clear view to the ground station, meaning external antennas. It works as an aid to locate most traffic, but not all and you must stay diligent with see and avoid as it is not an equivalent to an active traffic system or to TCAS.

Thanks, John, you are a great help. I think I understand it a lot better.

 

[John Collins]

This seems to be where the marketing doesn't meet the meat.

We're only five years out from virtually nobody using a portable if the regulatory mandates hold into 2020, correct?

Is it your opinion the installed non-portables don't have these flaws?

Billions spent for an "advisory only" system with some pretty significant data transport flaws. Not a great value overall.

Portable ADS-B Out is not safe in my opinion and should never be permitted. Portable ADS-B In, particularly for weather is great. Traffic on a portable is not something I would rely on, primarily for antenna reasons which can be overcome, but also because of sunlight readability, overheating, mounting, power and battery issues.

It is my opinion that the installed systems don't have the antenna issues, don't overheat, when displayed on panel mount GPS/MFD are sun light readable, are powered by the ship's electrical system, must meet standards for the ADS-B function and software reliability.

I have both installed in my aircraft. I love my iPad, but I fly with two on board and an iPhone. I use it for weather, information, situational awareness, flight planning. I don't keep it open all the time and it is not mounted. I use it when I need it. I depend on my panel equipment for the traffic advisory function, it is a great aid and helps me locate much of the traffic, but not all.

With respect to your last comment, you are mistaken if you think TISB traffic is the purpose of the system.

 

[denverpilot]

With respect to your last comment, you are mistaken if you think TISB traffic is the purpose of the system.

That's how it's being marketed to pilots to get them to spend a lot of money. I've never been fooled by the marketing spin, however.

It's an identification system. Really belongs in the DHS budget.

 

[airbrain]

I visited NorCal TRACON a couple of weeks ago and one of the other guests asked the controllers what ADS-B meant to them. This is just one senior controller's answer, but he said they just kept it disabled for now because almost nobody important (heavy metal) had it yet. He could only name one Brazilian aircraft that broadcast ADS-B out.

We asked what he would do with the ADS-B information if they did have it turned on and he thought for a few seconds and said that it provided basically the same information as RADAR currently does. While it gave them a tail number, if you aren't on a flight plan or flight following then they aren't talking to you anyway, so tail number is useless to them except to violate you. Right now if you violate while squawking 1200 and you land at an uncontrolled airport, they have no way to no who you are. With ADS-B, they can bust you more easily.

He wasn't being mean about it and emphasized that unintentionals aren't treated harshly - more about making sure it doesn't happen again. And I wasn't a cynic about the technology. I'm a techie and it seems cool. But the reality seems to be as some have already said. It makes the system cheaper for the FAA, more expensive for us, and the only benefit on the ATC end is better enforcement. Yay. Maybe the peer to peer will become useful someday.