Model 3 emergency take-over & slams on brakes

[systemBuilder]

Today while driving south on old middlefield road in silicon valley to get onto highway 101 south, I was in the left lane following a car when a flatbed truck maneuvered to leave the road in the right lane, causing my car to immediately lock up the brakes, suddenly halting my car. Luckily traffic was going only a few mph at the last intersection before the onramp or I would have probably been rear-ended.

I was very embarrassed by this computer generated mistake.

At no time did the flat bed pass into my lane, he was exiting and i think the truck bed seemed to swivel in my direction but posed no threat. Bad AI, imho. My last accident was in 1988. This happened yesterday (Aug 26th) at 6:40pm, 2018 3P+, no autopilot, no FSD.

 

[Lindenwood]

Sorry that happened. Sucks everyone is too embarrassed to report when the car saves them.

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[DeltaOne]

I was in the left lane following a car when a flatbed truck maneuvered to leave the road in the right lane, causing my car to immediately lock up the brakes, suddenly halting my car.

You don't say what type of road you were on, but I learned my lesson. I only use auto pilot on a highway or freeway where all the traffic is going in the same direction and there aren't any cross roads.

In fact, at the time of my purchase (March 2021), the Model 3 owners manual stated such. I believe the manual has been changed now.

I had two emergency braking events on two lane roads. Came here for advice and was shown the page in the manual and advised to only use auto pilot on a highway or freeway.

 

[drtimhill]

You don't say what type of road you were on, but I learned my lesson. I only use auto pilot on a highway or freeway where all the traffic is going in the same direction and there aren't any cross roads.

The OP didn't say he was using AP.

 

[jackmott]

Today while driving south on old middlefield road in silicon valley to get onto highway 101 south, I was in the left lane following a car when a flatbed truck maneuvered to leave the road in the right lane, causing my car to immediately lock up the brakes, suddenly halting my car. Luckily traffic was going only a few mph at the last intersection before the onramp or I would have probably been rear-ended.

I was very embarrassed by this computer generated mistake.

At no time did the flat bed pass into my lane, he was exiting and i think the truck bed seemed to swivel in my direction but posed no threat. Bad AI, imho. My last accident was in 1988. This happened yesterday (Aug 26th) at 6:40pm, 2018 3P+, no autopilot, no FSD.

If you have the footage, you can try submitting to the NHTSA as a safety issue. If they get a lot of reports it will spur action.

 

[hgmichna]

These reported events usually have some or most of the following in common.

The car suddenly braked fully, almost or entirely to a standstill.

If somebody had been behind me, he would certainly have rear-ended me. (But there is never anyone behind.)

The recognizable cause never moved suddenly towards my lane or even entered my lane.

I forget to mention whether the autopilot or cruise control was on or off.

I forget to mention whether I was on a freeway.

I forgot to press the dashcam button, hence no video.

 

[3sr+buyer]

I forgot to press the dashcam button, hence no video.

Yes, press the dashcam button to save the video. Maybe it is still there if there was not much driving (or sentry mode) after the incident.

The video of such an incident would be of interest both here and at Tesla.

 

[The Other Dan]

It's happened to me twice. Each time same setup...

Busy 2 lane highway. Lane each direction.
Doing about 45-50mph on AP. Speed limited by traffic, set to 60.
Oncoming semi, never entered my lane, was pretty much centered in his.
Tesla emergency braked, split second later I mashed on the gas to avoid getting rear ended. Dropped to maybe 25-30mph. Don't know if AI let off the brakes or if me getting on the accelerator kept it going.
Truck behind me broke hard, don't know if he got into ABS, but he did quickly start moving to the shoulder to not rear end me.

Car was 2 weeks old, so didn't have dashcam set up.

 

[Knightshade]

It's happened to me twice. Each time same setup...

Busy 2 lane highway. Lane each direction.
Doing about 45-50mph on AP.

So- user error.

AP is explicitly not intended for use on 2-way undivided roads, per the manual.

 

[Knightshade]

What, specifically, are you disagreeing with @jsight?

The manual literally tells you

Warning
Autosteer is intended for use on controlled-access highways with a fully attentive driver

A 2-lane road with oncoming traffic is not a controlled access highway.

Those are the types of roads FSDBeta is intended to be used on- but not AP.

 

[KenC]

It's happened to me twice. Each time same setup...

Busy 2 lane highway. Lane each direction.
Doing about 45-50mph on AP. Speed limited by traffic, set to 60.
Oncoming semi, never entered my lane, was pretty much centered in his.
Tesla emergency braked, split second later I mashed on the gas to avoid getting rear ended. Dropped to maybe 25-30mph. Don't know if AI let off the brakes or if me getting on the accelerator kept it going.
Truck behind me broke hard, don't know if he got into ABS, but he did quickly start moving to the shoulder to not rear end me.

Car was 2 weeks old, so didn't have dashcam set up.

When you get used to phantom braking, it takes less than a split second for your foot to respond. My speed drops about 1mph before I press the accelerator pedal. I'm a bit shocked your speed dropped that much.

Also, if you see that the vehicle behind you is so close that he would have to take avoiding action in an emergency braking situation, you should drive without AP or TACC. Use those when you don't run the risk of getting rear-ended, etc., for the first few months, to get used to them, and understand when and where they might give you false alerts. It seems like every car is different. For example, my car hasn't phantom braked since last Winter. Instead I get a bunch of forward collision warnings, in situations where I used to get phantom braking.

The last thought reminds me, you should always add what version of the software are you on. New cars, often come with versions that may be months old. I'm on 2022.22.8

Also, as others have noted, AP, is not officially supported for surface roads.

One last thought, was it late or early in the day? Did the semi cast strong shadows across your lane? Did you happen to glance at your display when it happened? Where did the cameras think the semi was situated? Sometimes, the cameras can be out-of-calibration.

 

[tm1v2]

Why are folks talking about Autopilot (TACC or Autosteer)? The OP wasn't using Autopilot.

 

[KenC]

Today while driving south on old middlefield road in silicon valley to get onto highway 101 south, I was in the left lane following a car when a flatbed truck maneuvered to leave the road in the right lane, causing my car to immediately lock up the brakes, suddenly halting my car. Luckily traffic was going only a few mph at the last intersection before the onramp or I would have probably been rear-ended.

I was very embarrassed by this computer generated mistake.

At no time did the flat bed pass into my lane, he was exiting and i think the truck bed seemed to swivel in my direction but posed no threat. Bad AI, imho. My last accident was in 1988. This happened yesterday (Aug 26th) at 6:40pm, 2018 3P+, no autopilot, no FSD.

Of course, my personal experience is that the car overreacts to vehicles exiting the lane in front of me. Your situation seems to be one of a vehicle exiting from the lane to the right of you. But, you point out it was a flatbed, presumably with a tail that overhangs the back, so that when it turns, the tail can swivel into the lane left of it. I consider that a dangerous situation and one where drivers can underestimate the risk of the overhanging tail. Without video, no one can really know how risky it was, but I'm not at all surprised that the car is more cautious than your average human when confronted with a swiveling flatbed.

 

[Knightshade]

Why are folks talking about Autopilot (TACC or Autosteer)? The OP wasn't using Autopilot.

The OP was not. The person to whom I was replying was though, so I was explaining AP is explicitly not intended for use in that type of situation.

What the OP experienced was just standard AEB--- which virtually all cars have now- some being better or worse than the implementation Tesla currently has.

 

[drtimhill]

One last thought, was it late or early in the day? Did the semi cast strong shadows across your lane? Did you happen to glance at your display when it happened? Where did the cameras think the semi was situated? Sometimes, the cameras can be out-of-calibration.

There is also the possibility that the car was responding to a legitimate issue the poster simply didn't notice at the time.

 

[DeltaOne]

There is also the possibility that the car was responding to a legitimate issue the poster simply didn't notice at the time.

I wonder if the OP knows about the three levels of AEB (Early, Medium, Late). Perhaps they could try Late.

 

[gearchruncher]

When you get used to phantom braking, it takes less than a split second for your foot to respond. My speed drops about 1mph before I press the accelerator pedal. I'm a bit shocked your speed dropped that much.

Human reaction time to a completely unexpected stimulus is well over 250ms. That's only 4 MPH per second deceleration. That's only 0.2G, which is basically the same as using regen. Meanwhile, real braking is well over 1G.

There is zero way a human can catch a real AEB event within 1 MPH. You're talking about very gentle decelerations because you're talking about when AP is driving, and that's just AP doing AP things. The OP had the car slam on the brakes when AP wasn't even engaged, which is AEB.

 

[MP3Mike]

I wonder if the OP knows about the three levels of AEB (Early, Medium, Late). Perhaps they could try Late.

AEB doesn't have three levels. FCW, Forward Collision Warning, does. But changing the FCW setting doesn't impact how/when AEB engages.