FJ use of Transponder Mode C
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My memory is vague on this one, but bear with me... in the Sentry about 10 years or so ago we had a spate of F3s reporting their Mode C at minus 1,400 feet. (similar to the Dublin story above?). This figure relates to receiving a Mode C response with just the bracket pulses but no height information contained within. The problem to the E-3 was that priority for height display on console was for the Mode C height and therefore we could not get a radar height response on these targets. Requests for information about these responses from the F3 PT was not forthcoming, but we believed that they resulted from Mode C being selected to standby rather than off in the cockpit(??).
Needless to say, the Sentry software was modified to disregard such low MC responses as it would be unlikely for the aircraft to be operating at such a low level (and wanting to be seen on Mode C) so we got radar reported height back onto the displays.
Needless to say, the Sentry software was modified to disregard such low MC responses as it would be unlikely for the aircraft to be operating at such a low level (and wanting to be seen on Mode C) so we got radar reported height back onto the displays.
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Not presuming anything, jto but fwiw it happened a lot so I don't believe it was finger trouble. And why would I rephrase the post to ask about primary radar when the issue is transponder use?
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Not sure of the position of the radar heads in the airspace you are talking about but I know in some areas primary and secondary radar heads were not co-located so the issue might have been to do with radar cover. Additionally, most of the ATC SSR radar heads were gated, can't remember the figure but I think it was about 7000ft/min (up or down), and if the value was exceeded the mode C was not shown on the screen.
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That might be part of it, pm. The radar heads, not the 7000 fpm that is, unless they were having a particularly exciting day out! I was intrigued by OAP's comment which perhaps hints the transponder was considered to be helping an opponent??
. We were bombers for Gawds sake 
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