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| Help! Help! I'm being repressed!  |
Just did a little reading on the subject and wanted to confirm what I've read. In regards to general aviation, if someone is flying in an area that doesn't have much, if any, radar coverage{very rural) would they have their transponder on? For the transponder to broadcast it has to pick up a signal. If it doesn't receive that specific signal it doesn't broadcast? Is the transponder broadcast how sites like Flight Aware track aircraft? If they did have their transponder on in a very rural area, could it appear that their transponder is being turned off and then back on again because it is loosing the "interrogation signal" and stops broadcasting it's position? Thanks | ||
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A Grateful American |
(USAF Planemonkey) Transponders are "interrogated" by radar or other means and then "respond". They are not like a "always transmitting" radio. Think more like a "fuzzbuster", it sits there in recive mode, and when it is "interrogated" by the speed radar, it "squawks" to you with light and beeps. There are several "modes" (types) and some allow less "interrogation" (over "radar busy" environments) and such. Been more than 25 years, so there is a lot more to it, but hope that helps. Yes, that is basically how "Flight Aware" follows. And any radio signal can be affected by various means and that can result in a target "appearing/disappearing", and in such cases that it is critical to traffic, radio contact with the aircraft will be attempted/established. There are lots of procedures for such things. "the meaning of life, is to give life meaning" ✡ Ani Yehudi אני יהודי Le'olam lo shuv לעולם לא שוב! | |||
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| Member |
flightaware can just track the target. i can see/hear low flying helicopters/airplanes, without transponder code on pc or cellphone. | |||
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| Member |
I may be wrong (it happens), but I believe Flightaware gets their info from a public ATC feed. This is how some operators have blocked their tail numbers which are then not available for tracking on the site. It gets more complicated now that ADS-B is in the house. Aircraft that have ADS-B Out do in fact broadcast their data without relying on interrogation from ATC. You can actually buy a receiver and track ADS-B aircraft yourself, up to and including military aircraft which you can't see on Flightaware. To go back to the OP's question, in most cases you don't even need a transponder if you're flying in rural areas and below 10,000 feet I believe. It's been a long time since I've flown GA, there might be a rule that says if you have a transponder you have to operate it even if the airspace you're in doesn't require it, but I can't be sure about that Peter. Mongo only pawn in game of life... | |||
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| Go ahead punk, make my day |
Lotsa rules, but in general aircraft have their transponders on when airborne. We fly Part 91 a lot and are out in the boonies often, but there is never any thought to flying with the transponder off even if we could. It's a tool that helps ATC and other aircraft avoid each other, so why not have it on. https://www.law.cornell.edu/cfr/text/14/91.215 | |||
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| Help! Help! I'm being repressed! |
I understand if you have it you might as well have it turned on, but I'm trying to decide if what I'm looking at is shady or could it be explained by the transponder losing signal and not broadcasting it's position? | |||
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| Go ahead punk, make my day |
Aircraft can fly low and their transponder is no longer received by ATC, esp in mountainous terrain. | |||
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| Rumors of my death are greatly exaggerated  |
ADSB which will be required in early 2020 will fill in the gaps which exist with ground based radar. It will track signals, generated by onboard GPS and use this data to present the position of the aircraft. No radar will be required to facilitate this. Their is more to it, but that's the down n dirty. "Someday I hope to be half the man my bird-dog thinks I am." FBLM LGB! | |||
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| Ammoholic |
That is all true, but the ADS-B mandate is (mostly) only for airspace that currently requires mode. Class B airspace (LAX, LaGuardia, etc), the thirty mile mode C veil around those airports, class C airspace (San Jose, Monterey, etc) above 10,000’ MSL (mean sea level) and not less than some number I don’t remember (1,500’?) AGL (above ground level. Basically, if one flies only in rural areas and not very high, the ADS-B mandate may not apply to them. One other point on transponders. While they do reply to interrogation, all the ones I’ve ever used also had an ident button. Pressing this button causes the transponder to “respond” even if not being interrogated and to keeps it up for several seconds (solid reply light instead of blinking). There must also be something about the signal sent as it causes the target to standout on the controller’s radar screen. | |||
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| Member |
Would need a lot more specific info to answer that, but in general it would be more shady to intentionally leave it off to try and hide your location. If you're in Montana it could certainly be a terrain issue, or something as simple as a malfunctioning xpdr that only works "sometimes". Mongo only pawn in game of life... | |||
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אַרְיֵה |
I personally know of one person who left his transponder off when flying very low over the ocean at night with no external lights, in an airplane that had auxiliary fuel tanks to facilitate a long flight. When he landed in a farmer's field at the end of one such flight, the customers he expected were not there to meet him; instead, he was greeted by DEA and other LE agents. הרחפת שלי מלאה בצלופחים | |||
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| Member |
During the events of 9/11, the hijackers turned off the transponders, causing the FAA to lose and then mis-identify the aircraft. "Dead Midgets Handled With No Questions Asked" | |||
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| Rumors of my death are greatly exaggerated |
True, but you will lose the utility of using your aircraft to actually go somewhere. If you live in rural Kansas or Nebraska and only fly around locally you’ll be just fine. "Someday I hope to be half the man my bird-dog thinks I am." FBLM LGB! | |||
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