Timeline for When should a transponder be used?
Current License: CC BY-SA 3.0
11 events
| when toggle format | what | by | license | comment | |
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| Dec 9, 2018 at 2:33 | comment | added | fjch1997 | I'd like to add that it also allows ATC to verify mode C readout by comparing against field elevation. So they don't have to ask "Say altitude passing" | |
| Sep 23, 2015 at 16:02 | comment | added | xpda | In the past it was recommended to turn off the transponder on the ground. I believe this was because a bunch of planes on the ground would show up on controllers' displays and make it hard to see the airborne planes. Now, filtering makes that a non-issue, and they recommend transponders on the ground so planes can be tracked for tower/ground controllers. | |
| Sep 21, 2015 at 19:21 | history | edited | voretaq7 | CC BY-SA 3.0 |
The FAA broke the HTML AIM...
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| Aug 27, 2015 at 21:47 | comment | added | voretaq7 | @CJBS As far as I can tell it's not a regulatory requirement on the ground (at least under Part 91 - Parts 121 & 135 may impose additional requirements). At larger airports with ground surveillance radar it may be an operational requirement though (i.e. ATC will ask you to turn on your transponder so they can see you on their displays). | |
| Aug 27, 2015 at 21:36 | comment | added | CJBS | @voretaq7 Thanks - good reference. I'm assuming 'airspace' doesn't include taxiing on the ramp or even taxiways (per the FAR), given that the ground isn't controlled airspace. | |
| Aug 27, 2015 at 18:47 | comment | added | voretaq7 | @CJBS FAR 91.215 would be the base regulation: Paragraph C says: While in the airspace as specified in paragraph (b) of this section or in all controlled airspace, each person operating an aircraft equipped with an operable ATC transponder maintained in accordance with §91.413 of this part shall operate the transponder, including Mode C equipment if installed, and shall reply on the appropriate code or as assigned by ATC. (Bolding mine - "required everywhere except Class G airspace" is my read of that regulation.) | |
| Aug 27, 2015 at 5:29 | comment | added | CJBS | If the above quotation is from the AIM, then it is recommended, not required (as you've noted). Note: I'm not asserting that it's not good practice to use ALT reporting when taxiing! Is there a FAR # that mandates any transponder use outside class A, C and the class B 30NM veil? | |
| Jan 12, 2015 at 20:57 | comment | added | voretaq7 | @rbp the standby mode runs the cavity tube heater (at least it does in the AT-150 I have), it just doesn't connect it to transmit replies when the transponder gets interrogated. Whether you do more damage cycling the heater on & off or letting it run all the time is debatable, but turning it off on your taxi back to the ramp does take about an amp off the electrical load which is something if your electrical system is marginal at low RPM. | |
| Jan 12, 2015 at 20:40 | comment | added | rbp | the other reason why we were taught to turn the xponder off on the ground is because older transponders had a cavity magnetron, which is a kind of high-voltage tube. The idea was to turn them off when not in use, to prevent them from wearing out, and to reduce the load on the electrical systems in old airplanes | |
| Dec 23, 2013 at 2:25 | vote | accept | xpda | ||
| Dec 23, 2013 at 1:44 | history | answered | voretaq7 | CC BY-SA 3.0 |