Around March 1, and for a few days afterward, I was looking at air traffic over the North Atlantic. During that time I saw icons I had never seen before. They were moving slowly at 'ground' level in regular patterns, hour after hour. They were in what appears to be open water, near the Lucky Strike thermal vent, south-southwest from Flowers Island. Some of the tail numbers were shown on the FAA.gov website as 'reserved' by San Francisco Airport. I emailed the gentleman who is shown there as a contact person. I received no reply from him. Shortly afterward, and since then, the icons have no longer appeared on my screen. Has anyone else seen these icons with the 'flame' and the 'wrench' symbols? Do you know what is going on out there?
Why would you contact the SFO airport about this ... ? It's not easy to avoid this as ground positions aren't unambiguous. When you receive a ground position, you need to choose from 8 positions around the globe. A local receiver does that by knowing where the receiver itself is. Then the closest of those 8 positions is chosen. For adsbexchange and how the feed system works, it's a bit more complicated. Actually those vehicles just shouldn't show at all, i'm not sure why they do. The icons should be self explanatory: maintenance / fire and rescue vehicles.
Why contact SFO contact person? Here is why: I did not understand the significance and movement of the icons. To find out, I went to the FAA.gov database, which said, only, that the tail numbers were reserved by SFO, and gave the name of the responsible person at SFO. Is it illogical to contact this person to clarify what is going on? Are aircraft tail numbers routinely assigned to fire trucks and repair trucks? If so, why put them out in the Atlantic Ocean, thousands of miles from SFO? Is that the closest of the 8 positions? Are there thousands more of these icons hiding all over the globe? Where are the 8 locations? (or) Where can I learn more on this subject?
It's complicated. As i said it's a decoding error basically, somehow our servers have a reference positions while they shouldn't have one and not decode the position. How they initially get that wrong position, i don't know. This is a rough explanation of ADS-B position decoding for ground positions: https://aviation.stackexchange.com/questions/27494/how-are-ads-b-surface-position-frames-decoded This is for airborne positions, ground positions are similar except for some details as described before: https://mode-s.org/decode/adsb/airborne-position.html
Actually ADSBx has been able to deploy feeders globally thanks to the dedication of the community. The signals are traffic from an otherwise hidden and undisclosed underwater base used for military deployment (we think). You probably didn't get a response because the registration is being spoofed. We think these vehicles are being used to monitor and defend some submariner or otherwise previously undetected base of operations for an as yet unknown ogranization.
Hi James, actually nothing sinister about these ones at all. They are known ground vehicles at SFO. The UAS prefix ones are United Airlines service vehicles. You can find them at every US airport that has a major United Airlines base. The others are airport ops vehicles. You can cross-check with other sites like FR24 if you select the 'show ground vehicles' tab. I suspect the reason they appeared in the Azores was a technical issue misinterpreting the lat and long co-ords. I've seen this happen before with some ground transmitters in Denmark which appear in the Atlantic ocean off Ireland. The actual longitude figure has 2 digits transposed from their real longitude location on the Danish coast which makes them appear in the middle of the ocean. SFO is approx 38N 123W. Although the co-ords for the above photo aren't given other than "near the Azores", it's interesting to note that 38N 023W is in that vicinity. I'm not certainly not clued up on the technical side of it but may help figure out where the gremlin is.
It's not a gremlin it's just how ground ADS-B works. One of 8 possible locations it can be due to precision.
