Originally Posted by
ABUSMAN
Thank you very much "Roger That" for your reply. It really helped deepening my understanding. Let me ask a bit more to clear still hanging fog in my brain.
1. To display ADS-B data of the target on the ATM screen, does it need special atenna or is it just a software upgrade of existing SSR?
2. Regarding the name of the waypoint, now I get why it does matter. ADS-C downloads what's in the FMS and compare the route with the filed route in the ATM. Fair enough. However it still doesn't answer the issue that I raised.For the NAT HLA, all coordinates that commercial aircrafts use, there're univeral 5 digit names of those using agreed coding rules as described in ARINC424. So it is not a problem as long as this is used both in the FMS and ATM system.
Problem comes when using the random route which include coordinates like N0500.0 E13530.0 (Half degree on the Longitude). It is neither a whole number nor a half degree LAT coordinate that NAT HLA uses. From a pilot point of view, we file a flight plan using a coordinate and insert this coordinate into the FMS. When inserting this coordinate, FMS fix name is created either 7 digit (05N135E) by default which doesn't show half degree or any name defined by a pilot. As a result it can't be the same between ATM(N0500.0 E13530.0) and FMS(Either 05N135E or ABCDE).
I hope my point is well delivered and any input would be highly appreciated.
1. Ads-b operates on 1090ES and depending on ground system implementation there are some variants of ADS-B supported by the aircraft system that limits access to some fields. There are mandates for many airframes these days of course and as long as the ground system either includes ads-b sensors/receivers as part of its surveillance network, or acquires/buys it in from another provider, then it’s a standard integration task for the surveillance engineering and assurance teams at most ANSPs. You mention HLA, and taking Shanwick and Gander’s airspace, they both use Aireon’s space based ADS-B service for this airspace, it can handle all variants of ADS-B, and they relay it to the service delivery points and in turn their trackers from which it serves their flight data processing functions and their display systems. In effect, they don’t need their own receivers because Aireon have them aboard their constellation (although some legacy ground systems may also be present for good reasons too).
2. This is where I start to run out of steam a little as I work with some technically outstanding colleagues who just know the detail of this stuff (so I don’t need to !). Let’s do this iteratively though … have a look in
https://www.icao.int/EURNAT/Pages/EU...F142A1E5BC9%7D . Specifically have a read through 2018_003(Rev01) as it contains descriptions of the interactivity using ARINC424. Bear in mind that ATC use what is flight planned and generally don’t use ARINC424 to display anything (remember ARINC424 like many things was developed as shorthand because of mobile database sizes. ATM systems don’t suffer from the same challenges as they generally have bigger memory capacities and they only need to cover their geographical areas, not over the entire route of every flight etc.).
it’s my understanding that ARINC424 reflects what is displayed on the FMS, not the actual coordinate as that can be interrogated - but that’s a pilot thing not a ground thing (which is more my thing). Your dispatch should provide a copy of the ATC flight plan so you know what we’ve got. The missing clarity is what the airborne systems do with the short code because I don’t believe when we receive data from ads-b and ads-c it’s in ARINC424 standard notation. . Again using the previous link, have a read at bulletin 2017-002_Revision 051 that contains the following:
“NOTE: In NAT airspace where unnamed, half-degree of latitude waypoints are used, waypoint display labels can be misleading (minutes can be truncated or rounded) and/or the FMC can create a generic label). It is imperative that crews check the expanded coordinates of all oceanic waypoints. Custom waypoints in aircraft navigation databases for half-degree of latitude points should use “Hxxyy”as introduced in Supplement 23 to ARINC 424 paragraph 7.2.5. See NAT OPS Bulletin 2018-003, “Waypoint Insertion/Verification Special Emphasis Items.”
Once you have a read, please ask another question and I’ll see if I can answer further. If you wish to take it offline, feel free to DM and we can find a way to have your questions answered. Meantime, hope this helps.