Since when have transponders been on for the VFR Fisk Arrival

Datadriver

Datadriver

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Datadriver
Years ago (2014 and earlier ) the NOTAM told pilots to turn their transponders to standby or off.

Sometime since 2014 this seems to have changed.

In the 2024 NOTAM there is no mention of this. It's as if whatever voodoo was overloading the local equipment is no longer a thing?

Does anyone know the technical explanation?
 
ADSB. Now other pilots ***** at you with your tail number… if you fly 89 or 91 kts… ;)
 
Datadriver said:
Years ago (2014 and earlier ) the NOTAM told pilots to turn their transponders to standby or off.

Sometime since 2014 this seems to have changed.

In the 2024 NOTAM there is no mention of this. It's as if whatever voodoo was overloading the local equipment is no longer a thing?

Does anyone know the technical explanation?
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The requirement was changed shortly thereafter. In 2016 or 2017, it was changed to "set transponder to standby unless you have ADS-B." In 2019, it was changed to "Leave transponder on throughout approach."

I don't know if the "overloaded equipment" thing really held water. However, prior to 2008 the airspace around Oshkosh was handled by Chicago Center; in 2008 it was transferred to Milwaukee Approach - This is a year-round thing. Milwaukee Approach now controls everything below 10,000 all the way up to where Green Bay approach takes over just south of Appleton. So it's possible that Milwaukee's equipment can handle it where Chicago Center's couldn't, and 08-14 were just an unnecessary holdover, but only an ATCer would know for sure.

However, ADS-B has changed things and I think the FAA wanted to ensure that people had the best traffic assistance possible in the world's busiest airspace. The "standby unless you have ADS-B" would have been due to the fact that TIS-B only shows equipped traffic and traffic that's within +/- 3500' and 15nm from other equipped traffic. Since lots of planes had yet to be equipped in that era, it was possible to have big holes in the picture if you weren't equipped.

With the 1/1/2020 mandate, by 2019 enough of the fleet was equipped that this wasn't an issue any more, so they had everyone turn their transponders on to provide a reasonably complete picture to everyone.
 
Never worked with ADS-B but I think the tag is more configurable than with just 3/3A. If that’s the case, it’s possible for ATC to reduce the amount of clutter on their displays. I know there’s still a provision allowing them to have an ADS-B aircraft to go to standby in high traffic areas though.

Old school mode 3/3A data blocks can be a definite problem with clutter if it’s overlapping a tag from an NAS assign code (VFR / IFR). It’s the same with standard formation flights. If all the wingman squawked a code, the overlap would hide lead’s tag. No different in a high traffic density area. Also, not sure how close the corridors are to the SSR interrogator but that number of aircraft could cause “ring around.” Used to see that a lot with some transponders when they got close to our SSR site.
 
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What is “ring around”? Just a conglomeration of airplanes that comes back as a big indiscernible blob on the screen?
 
455 Bravo Uniform said:
What is “ring around”? Just a conglomeration of airplanes that comes back as a big indiscernible blob on the screen?
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Well I thought I had a pic of it but I can’t find it. Anyway, if you can imagine a tag or just a 1200 code that’s near the radar sweep, and all of a sudden like 5 more duplicate tags / codes wrap around the display. Only lasts a few seconds but still annoying. The primary target stays put and accurate but the secondary spins around the display and you get “ring around.” I think mode S put an end to that phenomenon but I can’t confirm that.

Another thing ATC can do is suppress a nondiscrete code to reduce clutter. So a 1200 code would show up as a / that’s attached to the target & beacon control slash. Problem with that is, giving traffic calls on 1200s outside of the Fisk area to IFRs and VFR FF wouldn’t have altitude displayed. You’d have to unsupress the code to get that.
 
ktup-flyer said:
I’ve been flying in since 2017, and they’ve always been on
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Here’s the actual timeline’s and NOTAM instructions:

2015 and before: transponders to standby within 30 miles of OSH
2016-2018: non-ADS-B equipped aircraft transponders to standby within 30 miles of OSH (later amended to at or before RIPON), ADS-B out equipped leave transponders on
2019 to prevent: everyone leave on regardless of equipment
 
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