The purpose of ADS-B Out is to provide ATC with surveillance information. It does not replace radar, either primary or ATCRBS although some radars that have overlapping coverage may be eliminated. The US has an ADS-B Out mandate for 2020. ADS-B Out is broadcast only and does not have any receiver function. In the US, the FAA has attempted to sweeten the pot by adding services from the ground stations (GBT – Ground Based Transceiver). Aircraft that equip with ADS-B In capability can take advantage of additional capabilities, for example weather and traffic. Since not all airspace will require ADS-B Out in the US, there will be a substantial number of aircraft that it does not make economic sense to enter the airspace that mandates the ADS-B equipment. Most of these aircraft will be equipped with their existing Mode A/C transponders. TISB is a service that the GBT provides that broadcasts target information on non conforming traffic that is Mode A/C equipped. The TISB (Traffic Information Service Broadcast) seems only to be offered here in the US. Although if one has an ADS-B receiver they may receive ADSB via Air to Air from aircraft that are equipped with ADS-B Out, without radar stations feeding the GBT with aircraft traffic that do not have ADS-B installed, one obtains a very incomplete picture of the traffic in the local area. The US GBT will selectively broadcast the traffic position based on the location of the client aircraft that is equipped with ADS-B Out. In general, any target detected by radar that is within the client’s airspace area (15 NM radius and +/- 3500 feet, also sometimes referred to as the hockey puck because of its shape), will have its position broadcast by the GBT. An aircraft that is not equipped with ADS-B Out is not afforded the TISB service. The US GBT also broadcasts weather and other data such as airport NOTAMS on one of the two ADS-B links that the US supports. This is termed FISB (Flight Information Service Broadcast). We use two independent links, one called UAT (Universal Access Transceiver) that broadcasts on 978 MHz and is not based on a transponder. It may be used below 18,000 MSL. The other link is based on a Mode S transponder and is 1090ES. This is the international link, the one adopted by the airlines, and may be used at all altitudes and required for flight above 18,000 MSL. Some aircraft are being equipped with both links. Even though ADS-B In is not mandated, many aircraft are or will equip with a dual link receiver.
Outside of the US, it is my understanding that the GBT provide no services, they just link the aircraft to ATC.
I have a Garmin GDL88 which is a UAT based ADS-B Out unit with a dual frequency ADS-B In capability. I use my WAAS GPS a Garmin GNS530W as a position source. I see most traffic once I am within the service volume of a radar site and a GBT. At my airport, this occurs at approximately 400 AGL. At this point in time, only a few percent of the aircraft are equipped, so most of my traffic is based on TISB. I see ADS-B Out traffic when on the ground and above. About half of the US airline fleet is using ADS-B Out, although most of them are not at the mandated version that will be required by 2020. Most of the airline international aircraft are also equipped. Both Boeing and Airbus and the RJ manufacturers equip all new production with the compliant version of ADS-B.
Note, the GDL88 also takes the TAS or TCAS output and merges the two into a single traffic presentation to a MFD or GPS.
The current version of the ADS-B Out MOPS does not provide the next waypoint as a data element to be broadcast.
Mandatory ADS-B makes sense only if all applicable ATC is equipped with it
Absolutely not. Every airplane that radiates ADS-B can be seen reliably by all other airplanes having ADS-B receivers which are inexpensive. This is as good as the totally overpriced TAS boxes that almost nobody in GA has. There are plenty of affordable ADS-B receivers and you can build one yourself with a € 20 DVB-T receiver and a laptop. If everybody did ADS-B out, there would be no need for FIS style traffic information at all.
and looking at how little ATC is even Mode S equipped after all these years
Germany has been equipped for a long time, France even start giving out generic IFR squawks because they use the flight ID from Mode S to track you. The UK are certainly very much behind on this with all the Mode A equipped aircraft.
I know the glider community uses FLARM but I was not flying close to glider sites, or if I was then not at weekends (I usually fly on weekdays).
You find gliders hundreds of miles away from their airfield. Here they are the biggest traffic threat, even to airliners. If you listen to the ATIS of EDDS, 70% of it is about glider activity on a good day. The gliders are even in airspace C and D. Especially IFR with a cumulus layer, the transition is very dangerous because this is where gliders are. I once encountered 7 of them below one cloud that I was about to penetrate.
Absolutely not.
I was referring to ADS-B replacing radar, which is the main reason why Eurocontrol are interested in it, apparently.
This is as good as the totally overpriced TAS boxes that almost nobody in GA has
I think most new GA IFR aircraft come with a TAS system, or it’s an option which most customers choose. I have one, and it’s a very effective system. Many many more people have a transponder than have FLARM or ADS-B OUT and while that situation is bound to change, it probably won’t materially change for many years. After the Mode S wars, nobody has the appetite for what they see as yet another surveillance technology from which they, as they see it, get no benefit. Remember that the section of the GA community which poses the most risk (low flyers) is the same section which is least likely to equip with anything.
Most UK Mode A targets are actually Mode C but the pilot has switched off Mode C – because he has been trained that way, to enable a CAS bust without getting caught, or through not knowing the functions of the knob on the transponder.
In the UK, there is AFAIK zero history of powered GA – glider midairs, and presumably there is a reason for this, because there are about two inter- powered GA midairs per year. Is there different data from Germany? I guess people here keep away from known gliding sites, and lone gliders are very rare (much more rare than powered GA) because only very experienced glider pilots do that – like the guy who lent me the FLARM box to play with.
If I was going to routinely fly through gliding sites I would get a FLARM box for sure, but I suspect that in the UK it would provide minimal protection. And outside of gliding it is virtually useless.
I’m not sure why you are so anti-ipad Peter
Not so… I have an Ipad too, and use it, in the right situations. I don’t use it in the cockpit because it doesn’t do all I need (I would have to get a wifi connected Iridium satellite phone solution to achieve that, and even then I would lose various functions I now have) and there is nowhere to put it in the TB20 where it would be in view
The LH yoke has the emergency backup GPS whose audio output is wired into the intercom, for terrain warning purposes.
Also I would need a general means of disabling the touch screen, which isn’t possible unless you jailbreak it. Only a specific app can contain such a function. Jepp FD does, but Jepp TC doesn’t.
I was referring to ADS-B replacing radar, which is the main reason why Eurocontrol are interested in it, apparently.
I have recently talked to a DFS employee about this. He told me that there was a major incident where secondary radar failed for several minutes and on several occasions in an area spanning Southern German down to Croatia. All ATC units became blind for secondary radar. The nature of the incident was not clear (to the employees) but a best guess is a military exercise to demonstrate that it can be blocked.
Apparently DFS’ plans to decommission primary radar sites in favor of secondary radar (i.e. transponder returns) have changed radically based on this experience.
I think most new GA IFR aircraft come with a TAS system, or it’s an option which most customers choose.
If you look at SEPs, then it’s maybe 10% of all new aircraft or probably even less. Not that new SEPs have any relevance in numbers relative to the fleet size…
I guess people here keep away from known gliding sites, and lone gliders are very rare
That is impossible around here, there are hundreds of glider sites. Many gliders go touring, even when there are no clouds. Those machines are incredibly efficient these days.
If I was going to routinely fly through gliding sites I would get a FLARM box for sure, but I suspect that in the UK it would provide minimal protection. And outside of gliding it is virtually useless.
FLARM is not designed for motored aircraft, PowerFLARM is and no, it is not virtually useless, the contrary is true, even in the UK or especially there with IFR without ATC. A TAS is better but the cost is prohibitive and it does not display gliders which is even more important over here than transponder targets.
Power-Flarm gives you no azimuth information. It’s thus almost useless for traffic avoidance. I have flown with such boxes…
Even when you have azimuth, some 90% of the traffic is never spotted. Without it…
The nature of the incident was not clear (to the employees) but a best guess is a military exercise to demonstrate that it can be blocked.
Presumably ADS-B could be jammed the same way… so what does this mean for the future of radar and for replacing it with ADS-B? I am certain primary radar will stay for ever, and SSR is an established technology which does work.
Power-Flarm gives you no azimuth information. It’s thus almost useless for traffic avoidance. I have flown with such boxes…
Azimuth is better of course but in most cases, the PowerFLARM indication is enough. You can see from the range whether it’s coming closer and same with the altitude.
Even when you have azimuth, some 90% of the traffic is never spotted. Without it…
I spot pretty much all traffic I get on my PowerFLARM and virtually all traffic I spot or get reported by ATC/FIS shows on my PowerFLARM. I do not know why you rarely find traffic, I surely do.
Regarding not being useful in the UK, I remember that I was IMC in G and so was a US Hercules transporter and my PowerFLARM showed me where it was (very very close) and allowed me to coordinate a manoeuver.
Regarding not being useful in the UK, I remember that I was IMC in G and so was a US Hercules transporter and my PowerFLARM showed me where it was (very very close) and allowed me to coordinate a manoeuver.
What did you do?
Presumably you were under a traffic service?
I would agree that any traffic indication is better than nothing, but nothing currently around at any density (or likely to be around in any density for at least 10 years IMHO, due to slow adoption by the relevant GA sectors) gets anywhere near an active TAS system.
Quote from Tuesday’s WSJ:
“The report also noted that the FAA has warned “general aviation” pilots—mostly private pilots—they shouldn’t rely on ADS-B information to separate their planes from others in the airspace. Some general-aviation pilots relying on this data “inadvertently flew their aircraft into restricted airspace that was either unmarked or incorrectly located on their ADS-B devices,” the report said. The FAA subsequently cited these pilots with violations."
