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ADS-B OUT in the US - now mandatory in transponder-mandatory airspace

Finally, this has arrived.

And no doubt European regulators are watching it too.

Reading about it in the US AOPA mag is quite interesting. The FAA set up an automated monitoring system for the integrity of the transmissions, and currently, just 10 days into it, they are seeing 8% of the aircraft to be noncompliant in some way; basically systems where the installer has misconfigured it. But the system is slick; a pilot can email a request for a performance report, up to 30 days after any flight.

Exemptions are

  • aerobatic flight (they are aware that when upside down, etc, the antenna may be masked)
  • formation flight (only the formation leader needs to radiate)

Note also that Class D and E are not transponder-mandatory airspaces.

Interestingly you do not need ADS-B OUT to enter the US i.e. to fly through their Air Defence Identification Zone. This leads me to ask what is the purpose of this measure. They have not done much with Mode S, which is the only other means of real aircraft identification. And it cannot be a general measure to minimise mid-airs between GA, or even between GA and CAT except at big airports.

@ncyankee will be the expert on this

Administrator
Shoreham EGKA, United Kingdom

Peter, they are modernising their ATC. To do that you need to know where the aircraft are when they are near or in airspace. It allows more flexibility and more accuracy in ATC. RADAR is rather inaccurate.

EGTK Oxford

I’m led to believe that ATC in my area is not utilizing the extra info, aircraft tail number etc – they apparently have access to it with a few key strokes but prefer to request ident etc. The extra data apparently clutters up their radar screens in an undesired way so at least for now, it’s business as usual for them (I asked).

The main users right now seem to be pilots with ADS-B IN, aided in seeing and avoiding traffic more easily without ATC contact. Given that the volume of traffic is too high for more than a small number of planes to be on a Tower or Flight Following/IFR that may be a good thing… once pilots have learned not to turn away from every other plane within a couple of miles and thereby to avoid creating a hard to predict traffic flow. I’ve noticed some are still learning this, making a track that looks like a snake…

Last Edited by Silvaire at 11 Jan 22:57

ADS-B Out was always intended for surveillance improvements in the high density airspace around major airports and 10,000 feet and above. Traffic and weather was not part of the mandate because it is ADS-B In, but was an incentive for some GA aircraft to equip. Traffic is only an aid to visual acquisition and never intended to replace a tCAS or a TAS system. NPE (Non Performing Emitters) are typically due to bad installations and have always been around, but there hasn’t been much incentive for pilots to get their installations fixed. For about the last year or so, the FAA has been sending letters to owners telling them to get their installations fixed and starting back in 2016, the NPE aircraft were no longer receiving TISB service. My guess is that most pilots never noticed they were not receiving TISB service. In any event, now such aircraft will be excluded from the rule airspace. As of Jan 1, there were 118,162 aircraft equipped and about 9500 of which are NPE. In most cases, it won’t be difficult to get the NPE status fixed. A fair number are GTX330 installs that were upgraded to ES. These were incorrectly slide out, upgrade, slide in installations. They sorta worked because a typical installation previously had an ARINC 429 input from the GPS to the GTX which provided position but none of the required integrity and geometric altitude. These installations typically will need a serial output from the GPS added to connect to the GTX and have an appropriate configuration performed.

The FAA monitoring system has been in place for several years and now is fully automatic. All you need to do is conduct a flight in range of a ground station and go online and enter your aircraft data. A report is automatically generated and an email with a PDF of the report is returned, typically within a half hour.

The 118,000 equipped aircraft is about 55% of the fleet, but not every aircraft is required to equip and many simply avoid the rule airspace. Some will never equip and if they have a need to enter rule airspace, they can request permission one hour before entry into the airspace and in most cases it will be granted. Pilots can not make the request while airborne or they risk a violation according to current FAA policy. An equipped aircraft with a failure can request permission any time.

KUZA, United States

Peter wrote:

And it cannot be a general measure to minimise mid-airs between GA, or even between GA and CAT except at big airports.

I think we need to wait to see how that works GA vs GA but that also can be done without identification in “TCAS fashion”?
For GA vs CAT as you mentioned it is still old transponders, primary radars and procedural anyway

Peter wrote:

Interestingly you do not need ADS-B OUT to enter the US i.e. to fly through their Air Defence Identification Zone

Isn’t big N-tail marks is all what you need to comply with flying through an ADIZ? it is visual identification after all

Paris/Essex, France/UK, United Kingdom

One great thing about ADS-B IN is that the tail number of traffic shows up on your screen. Helps a lot when ATC either vector the other guy(s) or just call traffic, provided, of course, you have decent SA and listen to what’s going on around you. Conversely, it can really help spotting traffic that doesn’t talk to ATC.

In fact, it may well have saved my life a couple of months ago when I saw a target that wasn’t talking to ATC on the screen on a collision course, same altitude. Spotting traffic against the clutter of L.A. is fiendishly difficult, I wouldn’t have seen him. Approach control was crazy busy and didn’t call the traffic (they normally do, saying something like ‘traffic at your 9 o’clock, we’re not talking to him’). I decided to climb out of the way (flying a Cessna, wanted to try to get and stay visual) and sure enough, the guy – also a Cessna – flew right under me. Had I stayed at my altitude, it would have been a mid-air or at least a very, very close call.

In addition, you of course get the wx info for your destination airport, enroute wx, etc. Love it!

Ibra wrote:

Isn’t big N-tail marks is all what you need to comply with flying through an ADIZ? it is visual identification after all

Nope. You need a transponder and a flight plan (IFR or DVFR – Defense VFR).

Last Edited by 172driver at 12 Jan 01:27

Peter wrote:

Note also that Class D and E are not transponder-mandatory airspaces.



ESME, ESMS

Peter wrote:

This leads me to ask what is the purpose of this measure.

To be able to see other aircraft on your iPad and not crash into them. I love this measure and I wish EASA implements this ASAP. I’m not being sarcastic.

ESME, ESMS

Peter wrote:

Interestingly you do not need ADS-B OUT to enter the US i.e. to fly through their Air Defence Identification Zone. This leads me to ask what is the purpose of this measure. They have not done much with Mode S, which is the only other means of real aircraft identification. And it cannot be a general measure to minimise mid-airs between GA, or even between GA and CAT except at big airports.

As stated in my other post, the purpose is ATC surveillance improvements over radar. Flying thru the ADIZ does not require ADS-B Out, but US airspace within 12 NM of the coast line over the GOM requires ADS-B Out for 3000 feet and above, other locations require it at and above 10,000 MSL in E airspace. ADIZ requires aircraft with an electrical power system to have a transponder with mode C, but ATC is authorized to approve flights without a transponder.

For aircraft with UAT based ADS-B Out and not receiving ATC services, there is an anonymous mode that is available that hides identity but allows surveillance. The FAA is also allowing what is known as Privacy ICAO Address (PIA) to be assigned for Mode S transponders. The PIA is a 24 bit value that is not associated with a US tail number but within the ICAO code range assigned to the US. There are about 130,000 such addresses that are not related to an N number, of which the FAA is reserving 50,000 for PIA use. To obtain a PIA, one applies to the FAA thru a process and must use a call sign obtained from a private company. At this point, ForeFlight and Fltplan.com (Aka Garmin) provide such call signs. So the PIA is entered into the transponder for the ICAO ID and a call sign is loaded into the transponder as well (FFLnnnn or DCMnnnn). The intent of the program is to provide those interested in not being tracked by $100 receivers that can decode the ICAO address and know the N number, a means to do this. The PIA is not published or related to the call sign. The PIA can also be changed periodically, like 60 days. Using a PIA without FAA permission and following program rules will result in a violation.

KUZA, United States
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