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Phantom braking (TACC/AP) [Not AEB]
- Thread starter cciebryan
- Start date
Rustybkts
Member
Such as camera's not seeing ahead when the wipers refuse to wipe. What will the AI think when passing a truck in foul weather when all you can do is grit your teeth and drive straight as you pass through the bow wave.
Will emergency braking assistance work at all without radar when the camera area of the windscreen hasn't thawed as quickly as the rest of the windscreen?
Mine took ages last winder despite the main screen being completely clear. That heated area for the camera's takes ages to thaw out.
I've not seen the tweet but many talk about this. The only one I can find is when someone asked him about whether 4D processing change was going to cure it and he said he yes. 4D links images and objects together across time and not just living from frame to frame. Radar at that point in time was still in scope. People without the radar n the US but not the latest 4D software are still getting the problem, so its certainly not cured it taking it away.
I think we need to wait a little longer to see if it actually gets cured.
Rustybkts
Member
Drew57
Active ember
That's all right then... almost total reassurance it will continue happening.
You come to learn when it is going to do it. Now I subconciously hover my foot over the accelerator whenever I'm passing a lorry that is drifting to the right slightly, or approaching a sharp shadow. Its odd to me that it brakes when passing a lorry - as it usually does it when you're almost passed - at which point it would make more sense to accelerate to get beyond it.
There's something odd about this, lots of you seem to act like it's a daily life threatening experience, I've had is maybe 3 times in 21 months and it was no big deal. I use AP a lot, because of where I live every journey is on the M40 and I use it all the time. Either we drive differently or different cars react in different ways. I certainly don't hover over the accelerator.
I drove M40 - M25 - M3 -M27 on AP to Dorset last week with absolutely no excitement.
I drove M40 - M25 - M3 -M27 on AP to Dorset last week with absolutely no excitement.
Pagemakers
Active Member
Like you I use autopilot a lot. Drove from Manchester to Portsmouth and back a couple of weeks ago and had it about 4 times each way.
It IS a big deal and it will be an even bigger deal when somebody slams into the back of you at 70mph.
Mine was pretty bad , but since the last update 2021.4.18 for me the issue has almost gone away . The sudden slamming of the brakes has been replaced with a more manageable slowing down (c1500 miles in including a round trip to Cornwall).
I’m still traumatised though so my foot still hovers 1mm above the pedal at all times!!
I’m still traumatised though so my foot still hovers 1mm above the pedal at all times!!
Rustybkts
Member
I couldn't agree more. Every time it happens I bet the car behind thinks I am a prize Dick Head when the brake lights go on with a clear road ahead in perfect conditions.
If it happened to me following a car I may think that I am being "brake checked" which wouldn't be unreasonable.
I had my first real phantom braking experience last night on the A1 close to Peterborough Services heading north. I've had unexpected light/medium braking and auto-steer twitches before, but this was full-on braking. I was passing a Discovery towing a box trailer and I think it must have freaked the driver out. Sorry! Fortunately, nothing behind me. I was on TACC only and in Lane 3 with it set to 73mph. When using TACC, I tend to keep my foot on the accelerator, so I could give it a push and recover quickly.
I didn't use TACC for the rest of the way home - about another 80 miles. Not feeling confident about using it now. If someone had been coming up fairly fast behind me, things could have got interesting!
I didn't use TACC for the rest of the way home - about another 80 miles. Not feeling confident about using it now. If someone had been coming up fairly fast behind me, things could have got interesting!
I use it as a wake up alarm! I find with TACC I concentrate a little less, not much, just a little having confidence in the car to control my speed. On long journeys the mind does start to wonder. So passing a lorry and the car slamming on for no reason gives a nice, not so subtle reminder to concentrate on the road again 
Then your car must do something different to mine. For me it's super rare, and when it does happen my car slows for like a couple of seconds before I take over. No one's going to rear end me, my speed will have dropped from 70 to about 60 then straight back up again.
There must be some reason for the difference in experience.
Pagemakers
Active Member
I’m on my second Tesla and this phenomenon is the same on both cars. Next time it happens to you try not taking over (if it’s safe to do so ) and you’ll see your car slows down considerably more than 5 to 10 mph.
I’m on it like you but some drivers may not be and may be unaware of what’s happening and that’s how a serious accident could happen.
I’m on it like you but some drivers may not be and may be unaware of what’s happening and that’s how a serious accident could happen.
Drew57
Active ember
I envy you, seems like everyone else (including me) has the same experience and normally the braking is quite severe (in one, case straight from 70 to 30 & I didn't intervene because it was quiet & I was passing over a slower road beneath the dual carriageway).
On the first couple of occasions I didn't have anyone close behind but had it been in regular traffic, two seconds would have definitely caused a serious incident. Since that time I only use AP with my foot directly above the accelerator & most long motorway/dual carriageway journeys give cause for at least one intervention.
My wife will not let me use AP when she is in the car.
I don't use AutoPilot other than on motorways. I do occasionally get the shrill beeps from the Forward Collision Warning, it's a bit jumpy. I'll value it the one time I'm not paying full attention some day.
So had the cars speed limit changed to the 30mph road underneath? A mapping error? I'm not sure if that's what's called Phantom Breaking. Also a dual carriageway rather than a motorway, maybe that makes a difference.
The last time I got Phantom braking was at my usual spot Junction 10 on the M9. It's a big long junction and the car got about half way along and then decided that it needed to brake. I noticed that the speed limit changed to 35mph. I'd never seen or noticed that before. There are no roads under or over the road at that junction. There is a road parallel to the motorway, but that has a limit of 10mph (private road). As far as I am aware there are no 35mph speed limits in the UK. Can anyone think why it would change to that speed?
Pagemakers
Active Member
I get it on the motorway all the time.
Phantom braking = braking for no apparent reason. Nothing to do with mapping or speed limit changes.
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