I wonder why the FAA is so fussy about the data source. What is their genuine concern?
It is intended to be used by ATC for primary surveillance with the radar beacon system as a backup. The distance between aircraft will be able to be reduced and the greater amount of traffic will be able to be more efficiently accommodated. In order to meet the minimum criteria for separation, accuracy has to be close to the boundary between what unaided GPS and SBAS provide. GPS units must meet stringent latency requirements for the entire system that must be verified through the STC process. In addition, ATC equipment needs to have integrity data transmitted to the GBT sufficient to support the applications. Most GPS units do not have a means currently available to support this requirement.
The GNS480, the first WAAS unit has all of the data necessary to meet the criteria, but the data is only available on the ARINC 429 buss. This makes it impossible to configure with the available ARINC 429 ports and support a PFD or EHSI as it consumes all the available ports. With more serial ports available, Garmin used it for their GTX330ES on its products. Eventually they will add this capability to the GNS480, but it is not available yet. Serial position is available on the GNS480, but not with the mandated data.
Trig only supports the serial interface to provide position data and has had to reverse engineer the Garmin Serial interface. They are still awaiting FAA approval of this interface as the ones that are currently available are not economical when compared to using an installed GNS430W/530W or GTN. In their STC, Trig has to demonstrate that the system meets the total latency requirement and can provide the necessary integrity data. I fully expect Trig to integrate a WAAS GPS as an add on feature to their transponder, although this is not confirmed by them.
The ADS-B TSO for 1090ES comes in three flavors, TSO C166; C166A, and C166B. These variations self define themselves to the ground station. The FAA only cares what one does with a TSO C166B compliant system. For now, they won't use any data other than from a TSO C166B transponder that provides the required data and integrity. If the integrity is outside of the bounds that is required for surveillance, those aircraft will not be able to be mixed with compliant aircraft and will end up with greater spacing, possibly based on radar with the ADS-B being ignored.
Airborne aircraft will process all variations, but the traffic feature is not used for avoidance, just for enhanced see and avoid. I have a UAT ADS-B system installed in my aircraft and it gives excellent traffic performance, but would not be of any use outside of the US.
OK; many thanks. I can see it.
Eurocontrol here have the same ambitions (removing radar).
Did trig reverse engineer the Garmin output? Garmin publish their RS232 data stream. It's in the GNS430 IM, for example. I recall looking at it when I was doing the SN3500 project, to see if the OBS mode is flagged in there (it isn't). The KLN94 did (their data is also published in the IM).
I am amazed Garmin are still developing the GNS480. I know it's a great unit but I would expect the company to kill it ASAP. How long do you think database updates will carry on?
Garmin has indicated it will release one more software update for the GNS480 and it will include support for the serial interface to the ADS-B units. Although Garmin publishes their Aviation data interface, they don't publish it for other proprietary uses of serial data, example the XM receiver GDL69, the ADSB interface, and the cross feed interface.
I expect that Garmin will support the GNS480 from a maintenance point of view as long as they have parts, probably at least another 7 years. Database support is free money, why would they not support it as long as there are willing buyers.
Eurocontrol here have the same ambitions (removing radar).
In the US, radar is not being removed, just becomes a backup system. Some radar sites will not be needed, but the majority will be kept. The FAA will fuse the data from both sources and uses the most accurate at the time. Also, although I expect there will be high compliance by GA in the US to add ADS-B, it is not required in much of the airspace. ADS-B will be required (along with a transponder if it is not used for ADS-B) in the following airspace: above 10,000 MSL, Class B, Class C. A Cessna 172 at Podunk will have no need to upgrade. If it is installed and working, just like with a transponder, it must be on anytime in class E airspace (pretty much all airspace not in Class A, B, or C and above 700/1200 AGL).
I believe you'll also need ADS-B Out in what are currently the Mode C veils surrounding US Class B airspace areas (Class E airspace). As it currently is for transponders, this equipment requirement will be waivered for aircraft having no engine driven electrical system. So you'll still be able to fly your Cub with handheld radio only (no other avionics) into Class D controlled airports within the Mode C/ADS-B Out veils. With prior permission, for instance for a one-off flight, you'll also be able to fly the same aircraft in the Class B and C airspace itself.
In the long term, assuming ADS-B Out is successful, I can imagine FAA may remove the aircraft transponder requirement given that ADS-B using UAT does not require a transponder. They will not likely remove most ground based radar installations because primary radar can track non-compliant aircraft.
The very big carrot with ADS-B is that it really does open a way to cheap "GA TCAS".
In Europe, the authorities have no need for carrots; they simply mandate and "everybody complies" (having first hotly debated it on pilot forums).
So when we got Mode S we didn't get the TIS carrot like they got in the USA.
Now we might actually get TIS - because the authorities don't have to lift a finger to do it.
What would be the cheapest way for me to comply with ADS-B? Let's assume the KLN94/KMD550 is going to go... I have a GTX330 (2005 firmware).
I think ADS-B in Europe will be done on 1090, not UAT. Bookworm should know this stuff.
What would be the cheapest way for me to comply with ADS-B?
Borrow our Eurofox?
Almost nobody powered has Flarm currently, but as it doesn't cost anything, why not radiate the data?
Maybe not in Shoreham, but at my homebase most club aircraft have it by now.
I think ADS-B in Europe will be done on 1090, not UAT.
So far, no UAT in Europe, and I can't see it on the horizon. Given that the 966MHz are in a DME channel, your UAT probably interferes with the mandatory DME receiver.
In the long term, assuming ADS-B Out is successful, I can imagine FAA may remove the aircraft transponder requirement given that ADS-B using UAT does not require a transponder. They will not likely remove most ground based radar installations because primary radar can track non-compliant aircraft.
The FAA says no although AOPA has unsuccessfully argued the same point. Primary radar is rarely used as a backup when the ATCRBS fails. The transponder system is still in use for TCAS and 1090ES is a function provided by a mode S transponder. This won't happen in my lifetime, but then again, I am getting old.
