Message posted by lone wolf on December 25, 2005 at 13:04:10 PST:
So FIDOE is now a fix? Being able to decipher the transponder (Mode-C) only reveals squawk code and altitude, depending on the FAA ping. [The reason Passur monitors 1030 is to determine the type of interrogation.] I believe passur has two receivers on 1090 to get a fix on the location. They also need a FAA feed to convert the squawk code to something meaningful. I believe Passur does "filtering" based on the squawk codes, or the data is filtered before they get it. [Perhaps sanitised is a better word.] I know many of the military flights are squawking because you can hear the codes assigned on the scanner. Now I think when in formation, only one bird is squawking, hence the military flights need to ID how many in formation. While passur claims their data comes from surveillance, I'm not sure they don't use the flight plan as well. When you run passur in the playback mode, it is feeding your PC zipped files of data. You can get the names of these files using the Java console. If you read these data files, they do contain the fixes in addition to other data. If the surveillance was strictly passive, it would not know or need the flight plan. There is a spot near Bald Mountain where the radome can't be seen. [There aren't many places that Bald Mountain can't see.] If you go to this spot, the 1030 ping can't be heard, so clearly Bald Mountain has FAA radar in it (but of course there are probably many other radio devices on the mountain). [Use AM mode to hear 1030/1090] Such military/FAA joint sites are common, and are called JSS (Joint Surveillance Sites). I doubt there are places on the Nellis range that can't be pinged. Now there are spots along that route 95 flight corridor that can't be seen by radar. You can hear ATC tell the smaller aircraft (i.e. not in j92) that they can't be seen. I know from a pilot who had this happen that the transponder is still being interrogated. I don't know if the data is being filtered by the military before it reaches the FAA. Again, let me state, the Janets landing at the TTR do not change squawk codes or callsigns when landing. I don't see any audio on the net for TTR Janet landings, probably because nobody is interested. [I don't even recall if I recorded such audio.] However, I'd camped out at the TTR and watched them land. My recollection is the TTR doesn't even use separate approach and tower frequencies, but the plane just talks to the tower when doing it's approach. I think they are on Salt Lake Center prior to switching to the TTR. I don't recall if SLC ATC gives them the frequency for the TTR tower. Getting back to Groom landings, if you review the scanner audio, they generally switch from approach/tower at around 9nm. From Tikaboo Peak, you can see the Janets fly very low, with Pappose Mountain in the backgroud. About 9mn out would take them to the next pass, i.e. beyond Papose. I've suspected these fixes (LAS294052 BTY060030) in the flight plans are Pyramid and Planet, but there is no way to verify this.
In Reply to: Re: Janet and FIDOE posted by Ron on December 24, 2005 at 23:21:44 PST:
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