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#91
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"Chip Jones" wrote in message
... A couple of years ago we had a guy flying through GRB approach airspace always had bad Mode C. But it was only bad with GRB approach, no other facility had a problem with it. He had it checked at an avionics shop and they found nothing wrong. Yep, this kind of Mode C anomoly happens in ZTL airspace too. That's one reason we always go with pilot reported altitude over Mode C readout. First time I was called on an inaccurate Mode C by ATL, I took it to the shop. They said it was OK and serviced it anyway. ATL called me on it again but it's fine everywhere else, almost.... Anytime I fly from GSO towards CLT, GSO either can't see me, or gets an incorrect mode C for a short period of time. Can't see why one or the other. Can't see why there is an anomoly at all. On the other hand, I flew RDU towards CLT practically every week for 3 or 4 years. GSO never had a problem seeing me on that route. Just one of those things that awaits migration to better technology. |
#92
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"pilotjww" wrote in message ... Nice thread. A small nit: I fly a low-wing, and any ATC traffic alert inside of 4-5 miles and below my altitude will be hard to see without some maneuvering to remove my airplane's nose or wing from line-of sight. I expect even a high-wing will also have at least the problem of traffic under the nose. I get a lot of these alerts, where the traffic is a thousand or more below me, often unverified, and I find them useless. You might want to think carefully about the potential impact of erroneous mode C information. It happens. It has happened to me more than once (see earlier posts). It has caused me to pay attention to those "low and close" alerts by at least for a moment, pretending that it is at my altitude. At least it gives you something to scan for. Maybe you'll see that glider loitering at cloud base. |
#93
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"Newps" wrote in message news:9VQ0b.210033$Ho3.27525@sccrnsc03... Chip Jones wrote: Had I known that these aircraft were going to get so apparently close in the end without a visual, I would have vectored the Baron early in the interests of air safety (regardless of what the 7110 dictates) to avoid the alert. That is far and away the better procedure. I have had a few situations like that and I will never let it get to a safety alert status. The IFR guy will get vectored. It also saves time. I totally agree, but it requires that you recognize the situation and have time to deal with it. In my airspace I simply don't have the time to vector every IFR around potential VFR traffic because I am too busy slinging IFR's around IFR's or providing other IFR services. The avoidance of the alert to begin with is indeed better for all concerned IMO, but it is not always possible because of workload. Chip, ZTL ----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeed.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =--- |
#94
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"Steven P. McNicoll" wrote: wrote in message ... That's the policy created by a bunch of inward thinking idiots at FAA Headquarters (ATP). You are not in a position to make that judgment.. That's your opinion. |
#95
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Peter Duniho wrote: wrote in message ... [...] it seems that the air traffic procedures folks are primarily fooling themselves (so, what's new? ;-) when they don't consider an unknown secondary target returning Mode C data to be sufficiently radar identified for merging target safety action. Keep in mind that if ATC is not in radio communications with the radar target, they have no way to verify the Mode C readout. As such, it should be considered unreliable. Since an ATC instruction could include an altitude change instead of or in addition to a heading change, the rules need to account for that. That is exactly what a TCAS RA does, and it relies on "unverified" Mode C. But, a merging target vector should not include an altitude change unless the controller has the altitude available, and then only as a last resort to an avoidance vector. My personal opinion is that, generally speaking, the FAA folks who come up with ATC procedures do have a clue, and the procedures mostly make sense. Good thing TCAS isn't so strict about what it tags. I guess that's a matter of debate. A faulty Mode C readout could cause a TCAS unit to cause an accident, rather than avoid one. Well, so far it has only prevented accidents. Had it been used properly on the Swiss border, a lot of folks would still be alive today.. |
#96
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"Steven P. McNicoll" wrote: "Newps" wrote in message news:N3h0b.192923$Ho3.26290@sccrnsc03... That was cool. I would tag up the "VFR" pilot and run him thru FSDO. You have proof he was IMC. You'd have proof that he was in IMC only if he had collided with the guy at 7000 in IMC. How would that provide proof that the collision took place in IMC? |
#97
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wrote:
"unverified" Mode C. When a Mode C readout is wrong, where is the problem? Is the encoder producing bad data? Is the data path between the encoder and the xponder corrupting the data? Is the xpdonder corrupting the data? Is the RF pulse from the xponder being corrupted? Is the receiver not decoding it right? |
#98
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Montblack wrote: ("Capt. Doug" wrote) (pilots vs. controllers- what a softball game that would be!) Man on 3rd base....You are not authorized to cross Home plate. Repeat...hold short of Home plate! Person holding short of 1st base, you may now taxi back to the dugout - you're out. Ahh, a double play in the making, on a ball hit over the centerfielder's head. -- Montblack Dare I ask the classic A&C bit, to wit, 'who' is on first...'what' is on second....and 'I don't know' is on third? Doc Tony ;-) [suddenly...] George H. "Let's get serious [!] here, Doc! What we need are 'team' names! In effect, what is the 'team' name for the the ATC controllers and what is the 'team' name for the pilots? Something 'catchy' perhaps!" Chip: "Well, how's this: 'Air Wizards' for the ATC folks [pauses...] and 'TINJOCKEYS" for the pilots?" X: [JD/LL.B. type from one of the av groups!] "Objection! The name 'tinjockeys' is clearly an inequitable visual analogy when the other team bears the otherwise superlative name of alleged 'air wizards'!" Y: [quickly grabs the Black Robe from the chair nearest the KB and assumes an ad hoc judicial posture.... !] "Objection over-ruled!" X: "Exception!" Y: "Noted!" Doc Tony: "How about we take the acronym approach! What say ye to the "DAMNED" [Descend And Maintain Normal Equated Distance] for the ATC folks and the "CAVULARIOS" for the pilots?" George H. "Nahhhh. Simply "AIRS" for 'us' that fly versus "SEATS" for 'them' that sits!" Chip: [and duly noting George's comment.....] "Well, as an alternative, what say to the "SCOPES" versus the "GROPES" !" ;-) Ohhh, what harm. [from the other thread...and STILL at it...throat well coarse now! ] Jim Fisher: "SEND DOWN 50' OF ROPE.....fer cryin' out loud!" great flick, that one! [but to my utter surprise...talking about flicks...] Montblack: [doing the commanding officer to Detective 'Popeye' Doyle bit...] "You know your hunches have been wrong before, Doc, or have you forgotten about that?" ;-) Jim Fisher: [the man loves those old flicks! Reverts and gets very serious....indeed angry!!] "Six weeks my partner and I worked this case and WHO do we come up with...PETE DUNIHO fer cripes sake...now you gotta' give us that warrant!" [*later for 'Joel Weinstock'..the actual script line] |
#99
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wrote in message ...
That is exactly what a TCAS RA does, and it relies on "unverified" Mode C. As I mentioned, this is not as safe as people (i.e. you) would like to think. But, a merging target vector should not include an altitude change unless the controller has the altitude available, and then only as a last resort to an avoidance vector. Your original question was regarding why vectoring is not part of the ATC standard procedures for dealing with a VFR target. I'm simply answering that. You are correct that one could limit the vector to no altitude changes. But that's simply not how the handbook is written. As far as I know, the language used in the controller's handbook allows altitude changes any time a controller is supposed to vector an airplane. It would be a significant change, and would add even more complexity to the handbook, to call out this particular case as a situation where the controller is permitted to providing heading guidance but not altitude. I'm not interested in a debate, and I don't see why you seem to be itching for one. If you really want to debate the matter, call up the FAA and discuss it with them. They wrote the controller's handbook, not I. I guess that's a matter of debate. A faulty Mode C readout could cause a TCAS unit to cause an accident, rather than avoid one. Well, so far it has only prevented accidents. Had it been used properly on the Swiss border, a lot of folks would still be alive today.. I have a friend who would never wear a seatbelt, because she had a relative who had been thrown from a car in an accident and walked away unscathed. The logic she was using is similar to your use of a single example to justify the use of TCAS. I assure you that if controllers started using unverified Mode C returns to provide altitude changes for traffic avoidance on a regular basis, eventually someone would wind up at the same altitude of traffic that ATC thought they were moving them away from. The main reason that TCAS doesn't cause accidents today is that it's used in a way that is unlikely to cause accidents. Airplanes that are in IMC are being positively controlled by ATC, and the TCAS should only provide a warning when ATC has made an egregious error. That doesn't happen very often. Furthermore, the airplanes involved are both under radar control, so even though the TCAS doesn't know it, the Mode C *has* been verified. Airplanes that are in VMC, whether under positive control by ATC or not, have the ability to use the TCAS to help them *spot traffic*, rather than just blindly trust the TCAS to tell them what to do. The pilots can then make a course adjustment as appropriate, based on *what they see*. The controller rules are not written to allow things that are "mostly safe". They are written to try to make sure that the controller's actions are 100% safe in ALL situations. In cases where the controller is unable to know for certain that they are able to separate traffic, the controller is simply not allowed to attempt it. As such, an unconfirmed Mode C readout is simply not a piece of information that a controller is allowed to use for positive control of another aircraft. It's sort of the Hippocratic Oath of air traffic control. Whatever else they do, a controller should not make the situation worse. Pete |
#100
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"Maule Driver" wrote in message
om... "pilotjww" wrote in message ... Nice thread. A small nit: I fly a low-wing, and any ATC traffic alert inside of 4-5 miles and below my altitude will be hard to see without some maneuvering to remove my airplane's nose or wing from line-of sight. I expect even a high-wing will also have at least the problem of traffic under the nose. I get a lot of these alerts, where the traffic is a thousand or more below me, often unverified, and I find them useless. You might want to think carefully about the potential impact of erroneous mode C information. It happens. It has happened to me more than once (see earlier posts). It has caused me to pay attention to those "low and close" alerts by at least for a moment, pretending that it is at my altitude. At least it gives you something to scan for. Maybe you'll see that glider loitering at cloud base. If ATC has you verified and another target unverified indicating a safely separated altitude, is it SOP to call traffic just in case? Will the controller make use of a previous report ("he's wa-a-ay below me") in deciding whether to do so? -- David Brooks |
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