Poll : Highway Phantom Braking Frequency

[EVNow]

Here is a poll to crowdsource Highway Phantom Braking experience stats. This is for Vision only - so you should either have no-radar Tesla or you are on FSD Beta.

By frequent, I mean, it is so much that it actually prevents you from using AP on highways or you take precautions when using it. Rare means you experience once in a while (say once in 100 miles or so), so you don't consider it when using AP on highways.

The poll is broken up by following distance to see if there is any correlation between frequency of phantom braking & following distance.

Note : Public Poll

 

[Sandor]

Here is a poll to crowdsource Highway Phantom Braking experience stats. This is for Vision only - so you should either have no-radar Tesla or you are on FSD Beta.

By frequent, I mean, it is so much that it actually prevents you from using AP on highways or you take precautions when using it. Rare means you experience once in a while (say once in 100 miles or so), so you don't consider it when using AP on highways.

The poll is broken up by following distance to see if there is any correlation between frequency of phantom braking & following distance.

Note : Public Poll

For the Beta FSD, some of the Phantom Braking (not all, just to be clear) are the "new and improved" speed sign read and obey. The SW right now will change the speed that I'm happily cruising at (80 mph usually on I-15/I-215) to something like 55, 65 or 70 based on some traffic sign that it sees. For me it started around 10.6 I think.... Thankfully it always does it in the same spots so I'm ready to scroll-up the speed back to 80. But it is beyond annoying. In contrast my wife's Y on the 2022.4.5 non-beta FSD never has these issues... Hopefully the single stack will solve this

To clarify my vote: It happens more often than each 100 miles, but I'm still fully using Beta FSD on my long commute. It's been worth the $5k I paid for it as far as I care, based on the increased comfort of the daily commute.

 

[sleepydoc]

I think you should specify/clarify TACC vs AP vs FSD. Also AEB vs PB. AEB events are typically more dramatic - alarm goes off, red steering wheel on the screen, much harder braking. PB (in my mind) are the random slowdowns of varying intensity/magnitude for no clear reason.

On my last long drive i experienced a PB event every 15 minutes or so. They were generally minor (about 5 MPH) and about the deceleration/intensity you'd get from regenerative braking. It's not enough to make me quit using TACC/AP but definitely annoying and enough that I tend to keep my foot on the accelerator because I don't want someone to plow in to me. Someone in another thread described TACC as 'useful but flawed' - I think that's a pretty apt description.

 

[momo3605]

I think you should specify/clarify TACC vs AP vs FSD.

Why? Phantom Braking is caused by Adaptive Cruise. On the highway, FSD uses AP (vision) code base, and they both use the same TACC. It's all the same.

 

[EVNow]

I think you should specify/clarify TACC vs AP vs FSD.

Can't have too many variables in the poll, unfortunately. Ideally we should do this with a questionnaire instead of a poll.

 

[Daniel in SD]

Oops didn't realize poll was Tesla Vision only.

 

[S4WRXTTCS]

I think it would be better if it defined what frequent was.

I picked frequent PB because it exceeds a threshold of one moderate severity PB event per 1000 miles.

 

[EVNow]

I think it would be better if it defined what frequent was.

I picked frequent PB because it exceeds a threshold of one moderate severity PB event per 1000 miles.

That is too severe a cut off. I’ve given a ballpark of 1 in 100 miles as “rare”.

Rare means you experience once in a while (say once in 100 miles or so),​

 

[Gilliland]

Why? Phantom Braking is caused by Adaptive Cruise. On the highway, FSD uses AP (vision) code base, and they both use the same TACC. It's all the same.

I think we have too many different definitions of phantom braking for this survey to give useful results. From my perspective, phantom braking has nothing to do with TACC. TACC often causes annoying unwarranted slowing, very often in fact, but phantom braking is much more severe and relatively rare. Obviously others here see it differently, which is fine, but without a common definition the survey won't give meaningful results.

By frequent, I mean, it is so much that it actually prevents you from using AP on highways or you take precautions when using it. Rare means you experience once in a while (say once in 100 miles or so), so you don't consider it when using AP on highways.

If I ignore my own views and instead base my answer on the TACC-based slowing, I still have no idea how to respond. In my experience, TACC-based slowing occurs all the time on the open highway - generally every mile or so, sometimes several times in a single mile - but even though it is exactly the opposite of "rare", it does not at all discourage me from using TACC, AP, or FSDBeta. In my own experience, I have never seen it create any kind of danger. It's just annoying - slowing down and then speeding up for no good reason. Sometimes the cause is obvious, but still unwarranted. Other times, no cause can be discerned at all.

Of course, I never find myself in "rush hour" scenarios. Maybe in a bumper-to-bumper race to get to work or get home from work, it might be a bigger concern. I don't think I'd even attempt to use any kind of cruise control in those situations.

 

[EVNow]

TACC-based slowing,

Not sure what you mean by TACC based slowing. Is that slowing because the car in front slowed ?

PB is sudden braking for no reason and we are not talking about slowing by a few mph - but quite a bit.

One thing to note is AP may slow down because it thinks the car in the next lane might come into your lane (or something similar). I'd not call those PB.

PB is basically the car thinking something (usually stationary) is in the path of the car and the car will crash into that unless stopped. So the car suddenly applies brakes and slows down by 10 or 20 mph or more - but there is really nothing in the path of the car.

 

[sleepydoc]

If I ignore my own views and instead base my answer on the TACC-based slowing

what's the difference between 'slowing' and 'braking?' functionally, they're the same - the car decelerates. You can brake gradually or brake hard and Tesla will actually put the brake lights on for regenerative braking whether the physical brakes are used or not.

 

[sleepydoc]

Not sure what you mean by TACC based slowing. Is that slowing because the car in front slowed ?

PB is sudden braking for no reason and we are not talking about slowing by a few mph - but quite a bit.

One thing to note is AP may slow down because it thinks the car in the next lane might come into your lane (or something similar). I'd not call those PB.

PB is basically the car thinking something (usually stationary) is in the path of the car and the car will crash into that unless stopped. So the car suddenly applies brakes and slows down by 10 or 20 mph or more - but there is really nothing in the path of the car.

My interpretation of TACC-slowing is when the car randomly slows down for no reason while using TACC. I've had it slow anywhere from 5 MPH to 20 MPH in all sorts of conditions but frequently when there is a clear road and no reason to slow.

 

[ZenRockGarden]

None, zero, never. No phantom braking in 1000 miles use of AP on multi-lane freeway

 

[EVNow]

My interpretation of TACC-slowing is when the car randomly slows down for no reason while using TACC. I've had it slow anywhere from 5 MPH to 20 MPH in all sorts of conditions but frequently when there is a clear road and no reason to slow.

Whether you are using TACC or AP or NOA - a 20 mph sudden drop in speed would PB … 5 mph, not sure.

 

[Gilliland]

Not sure what you mean by TACC based slowing. Is that slowing because the car in front slowed ?

PB is sudden braking for no reason and we are not talking about slowing by a few mph - but quite a bit.

One thing to note is AP may slow down because it thinks the car in the next lane might come into your lane (or something similar). I'd not call those PB.

PB is basically the car thinking something (usually stationary) is in the path of the car and the car will crash into that unless stopped. So the car suddenly applies brakes and slows down by 10 or 20 mph or more - but there is really nothing in the path of the car.

I'm talking about the car slowing down for no good reason. It may be reacting to something in the next lane that it need not react to, or it may be reacting to nothing at all. It slows down for no good reason. 5 MPH - no big deal. 20 MPH - still no big deal unless it happens in 1 second. Spread out over 5 to 8 seconds - no big deal. This is the kind of deceleration that you get when you just take your foot off the accelerator - regen braking alone. I don't consider any of this to be phantom braking. But apparently many others do.

For me, phantom braking is when the car slams on the brakes hard enough to throw you into your seatbelt, locking it up. That is generally accompanied by audible warnings and red steering wheels flashing before your eyes. It's not caused by TACC. This is the kind of problem that will get the attention of regulatory agencies.

I'm not trying to get anyone to agree with my definition, though I know there are at least a few who do. But even among those many of you who look at it differently, there is more than one definition of phantom braking, or there are various thresholds for it.

 

[Bouba]

I think we have too many different definitions of phantom braking for this survey to give useful results. From my perspective, phantom braking has nothing to do with TACC. TACC often causes annoying unwarranted slowing, very often in fact, but phantom braking is much more severe and relatively rare. Obviously others here see it differently, which is fine, but without a common definition the survey won't give meaningful results.

If we can’t agree on the definitions of the events then let’s change the poll to how we feel..
An annoying event
A what the hell event
It nearly killed me event
Etc

 

[Dcam]

Mostly on two lane highways when an oncoming car approaches.

 

[Alex10000]

Just to clarify, I'm curious if the PB incidents happen mostly (or only?) during cruise control? How frequent is it when driving without cruise control? Thank you!

 

[JohnB007]

Just to clarify, I'm curious if the PB incidents happen mostly (or only?) during cruise control? How frequent is it when driving without cruise control? Thank you!

This poll probably no longer applies as newer software behaves differently.

In my case, I feel pretty much no serious PB now but there was a time when it was giving me issues. Light PB still happens but they are mild enough that I can ignore those.

And this is with FSD on. Without AP/FSD activated, of course, I get zero PB.