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Why not just turn it off? As a fellow driver I feel rather uneasy knowing my safety depends on your ability to predict your car's phantom braking... And by une

Why not just turn it off? As a fellow driver I feel rather uneasy knowing my safety depends on your ability to predict your car's phantom braking... And by uneasy I mean unsafe enough that I believe you literally should not be allowed to drive like that.

bob33212 5y ago
Don't ever go to a bar in the evening, you will be very uneasy when you see people 5 drinks deep pull out their keys.
- dataflow 5y ago
  What's your point? Last time I checked drunk driving was illegal.
  - zild3d 5y ago
    It is, but your safety still depends on people abiding by that law, which they don't.
    - dataflow 5y ago
      So what? We should get rid of the law and legalize drunk driving then? Again: what's your point?
smileysteve 5y ago
For braking; as a following car, you're technically following too close if you can't come to a complete stop if the car in front of you does. Every car is capable of doing this; every car is one transmission / differential / electric motor lockup away from stopping its drive wheels immediately. In an internal combustion engine there are a few other possibilities including a thrown piston or rod, a significant lack of oil
- dataflow 5y ago
  > For braking; as a following car, you're technically following too close if you can't come to a complete stop if the car in front of you does. Sure, and have you heard of brake checks? They're (very) illegal despite what you said for a reason. https://en.wikipedia.org/wiki/Brake_check https://en.wikipedia.org/wiki/Brake_check Brake testing and tailgating are examples of aggressive driving, and both may be punishable as vehicular assault, careless or reckless driving, or vehicular homicide if death occurs.
  - frumper 5y ago
    You have to be able to stop because they may stop for reasons other than illegal brake checking.
    - dataflow 5y ago
      Sure, I agree. Nobody said you don't need to be able to stop.
      - aembleton 5y ago
        Ideally though you should be able to stop before hitting the car in front.
        dataflow 5y ago
        Yeah, ideally you would.
- serf 5y ago
  >Every car is capable of doing this; every car is one transmission / differential / electric motor lockup away from stopping its drive wheels immediately. yeah, but these risks of mechanical lockup are usually better mitigated against because they're an understood risk. Driveshaft lockups can occur, generally because an appliance on either side of them failed -- certain manufacturers mitigate this by very simply using mechanisms that are unlikely to ever break, and some manufacturers go an extra step and use BreakBolt style fasteners that will destroy themselves in the event of a lockup that torques them harshly. An engine seize event doesn't stall or stop a vehicle that uses a CVT (most low-end 'automatic' cars on the market), it just creates additional engine braking pressure -- and before CVTs were in common use we used traditional torque converter automatics that failed similarly.. this is one of the major features of a hydro-mechanical linkage element like a torque converter. Many CV axle designs now incorporate straps to limit movement during a failure, to prevent wheel lock or steering lock. New style manuals can automatically engage the clutch during an engine seize event, limiting the physical reaction from the car during the event. Shit still happens, wheel locks are uncommon but they still exist; but I think it's safe to say that people are waiting to hear what Tesla's engineering answer will be to the whole 'suddenly-stopped-car' problem.
jsight 5y ago
Because it generally works really well, and most of the phantom braking is generally 5-10 mph drops that aren't as dramatic as the on in the forum post being referenced.
- dataflow 5y ago
  How often do you get a phantom brake > 5-10mph?
  - jsight 5y ago
    Twice in the last year (>13k miles total). One of them involved a truck pulling a fifth wheel that crept into my lane, but not far enough to warrant an emergency braking response. The other was a similar situation involving a vehicle merging in a short merge lane. I think the car was anticipating that the person was merging due to the short space that they had, but in reality they were slowing to wait on me to pass. Both involved the car jumping immediately to a full on panic braking type solution when no collision was imminent or likely. To be clear, I don't know that these involved dropping >10 mph either... but it definitely would have if I hadn't intervened.
elif 5y ago
By phantom braking, they mean a drop of 10-20 mph to add a safety margin in the potentially hazardous scenario of a car travelling opposed into your lane of travel. It is scary to people because the Tesla makes an unsettling alert noise at the same time the vehicle speed changes slightly. The only way this would result in an accident is with someone else speeding and tailgating. I'll get my tiny violin and 360 dashcam ready for that one.
- dataflow 5y ago
  > a drop of 10-20 mph > the vehicle speed changes slightly 20mph is not a "slight" change. That's easily a full third of your speed in a freeway (or a quarter if you're speeding), literally the difference between a street and a freeway. And that's easily half your kinetic energy you'd be losing. > The only way this would result in an accident is with someone else speeding and tailgating Surely you can't pretend you've thought of every possible scenario this could turn into an accident? If nothing else, people can momentarily miss the fact that the car in front of them randomly slowed down 20mph, especially when other cars are maintaining their speeds. Doubly so if they're glancing somewhere else to change lanes or watch out for other dangers or whatever. A million things can go wrong that I can't pretend to think of, and I'm shocked you just so confidently ruled them all out. As I see it, just because some of us are mortals, that doesn't excuse letting small mistakes bare our mortality in the middle of a highway.
- HWR_14 5y ago
  > The only way this would result in an accident is with someone else speeding and tailgating. Let's examine a Tesla traveling at 60 mph starts full on breaking to 40mph, and the person behind them is traveling at (1) the same 60mph and (2) is maintaining the recommended separation for 60 mph and (3) has instant breaking (bonus condition). The driver behind has 2.5 seconds to react to avoid a collision. The average human reaction time for a driver who is expecting breaking soon is 1.5 seconds, but this "phantom breaking"'s deceleration comes out of nowhere. And the average car doesn't have instantaneous speed changes. In fact, an F-150 with similar automatically computer activated breaking would be a coin flip to avoid a collision, certainly a matter of a couple of feet. I've never heard of a better case that even these "safety features" should be disallowed on public roads.

bob33212 5y ago

Don't ever go to a bar in the evening, you will be very uneasy when you see people 5 drinks deep pull out their keys.

dataflow 5y ago
What's your point? Last time I checked drunk driving was illegal.
- zild3d 5y ago
  It is, but your safety still depends on people abiding by that law, which they don't.
  - dataflow 5y ago
    So what? We should get rid of the law and legalize drunk driving then? Again: what's your point?

smileysteve 5y ago

For braking; as a following car, you're technically following too close if you can't come to a complete stop if the car in front of you does. Every car is capable of doing this; every car is one transmission / differential / electric motor lockup away from stopping its drive wheels immediately. In an internal combustion engine there are a few other possibilities including a thrown piston or rod, a significant lack of oil

dataflow 5y ago
> For braking; as a following car, you're technically following too close if you can't come to a complete stop if the car in front of you does. Sure, and have you heard of brake checks? They're (very) illegal despite what you said for a reason. https://en.wikipedia.org/wiki/Brake_check https://en.wikipedia.org/wiki/Brake_check Brake testing and tailgating are examples of aggressive driving, and both may be punishable as vehicular assault, careless or reckless driving, or vehicular homicide if death occurs.
- frumper 5y ago
  You have to be able to stop because they may stop for reasons other than illegal brake checking.
  - dataflow 5y ago
    Sure, I agree. Nobody said you don't need to be able to stop.
    - aembleton 5y ago
      Ideally though you should be able to stop before hitting the car in front.
      - dataflow 5y ago
        Yeah, ideally you would.
serf 5y ago
>Every car is capable of doing this; every car is one transmission / differential / electric motor lockup away from stopping its drive wheels immediately. yeah, but these risks of mechanical lockup are usually better mitigated against because they're an understood risk. Driveshaft lockups can occur, generally because an appliance on either side of them failed -- certain manufacturers mitigate this by very simply using mechanisms that are unlikely to ever break, and some manufacturers go an extra step and use BreakBolt style fasteners that will destroy themselves in the event of a lockup that torques them harshly. An engine seize event doesn't stall or stop a vehicle that uses a CVT (most low-end 'automatic' cars on the market), it just creates additional engine braking pressure -- and before CVTs were in common use we used traditional torque converter automatics that failed similarly.. this is one of the major features of a hydro-mechanical linkage element like a torque converter. Many CV axle designs now incorporate straps to limit movement during a failure, to prevent wheel lock or steering lock. New style manuals can automatically engage the clutch during an engine seize event, limiting the physical reaction from the car during the event. Shit still happens, wheel locks are uncommon but they still exist; but I think it's safe to say that people are waiting to hear what Tesla's engineering answer will be to the whole 'suddenly-stopped-car' problem.

jsight 5y ago

Because it generally works really well, and most of the phantom braking is generally 5-10 mph drops that aren't as dramatic as the on in the forum post being referenced.

dataflow 5y ago
How often do you get a phantom brake > 5-10mph?
- jsight 5y ago
  Twice in the last year (>13k miles total). One of them involved a truck pulling a fifth wheel that crept into my lane, but not far enough to warrant an emergency braking response. The other was a similar situation involving a vehicle merging in a short merge lane. I think the car was anticipating that the person was merging due to the short space that they had, but in reality they were slowing to wait on me to pass. Both involved the car jumping immediately to a full on panic braking type solution when no collision was imminent or likely. To be clear, I don't know that these involved dropping >10 mph either... but it definitely would have if I hadn't intervened.

elif 5y ago

By phantom braking, they mean a drop of 10-20 mph to add a safety margin in the potentially hazardous scenario of a car travelling opposed into your lane of travel. It is scary to people because the Tesla makes an unsettling alert noise at the same time the vehicle speed changes slightly. The only way this would result in an accident is with someone else speeding and tailgating. I'll get my tiny violin and 360 dashcam ready for that one.

dataflow 5y ago
> a drop of 10-20 mph > the vehicle speed changes slightly 20mph is not a "slight" change. That's easily a full third of your speed in a freeway (or a quarter if you're speeding), literally the difference between a street and a freeway. And that's easily half your kinetic energy you'd be losing. > The only way this would result in an accident is with someone else speeding and tailgating Surely you can't pretend you've thought of every possible scenario this could turn into an accident? If nothing else, people can momentarily miss the fact that the car in front of them randomly slowed down 20mph, especially when other cars are maintaining their speeds. Doubly so if they're glancing somewhere else to change lanes or watch out for other dangers or whatever. A million things can go wrong that I can't pretend to think of, and I'm shocked you just so confidently ruled them all out. As I see it, just because some of us are mortals, that doesn't excuse letting small mistakes bare our mortality in the middle of a highway.
HWR_14 5y ago
> The only way this would result in an accident is with someone else speeding and tailgating. Let's examine a Tesla traveling at 60 mph starts full on breaking to 40mph, and the person behind them is traveling at (1) the same 60mph and (2) is maintaining the recommended separation for 60 mph and (3) has instant breaking (bonus condition). The driver behind has 2.5 seconds to react to avoid a collision. The average human reaction time for a driver who is expecting breaking soon is 1.5 seconds, but this "phantom breaking"'s deceleration comes out of nowhere. And the average car doesn't have instantaneous speed changes. In fact, an F-150 with similar automatically computer activated breaking would be a coin flip to avoid a collision, certainly a matter of a couple of feet. I've never heard of a better case that even these "safety features" should be disallowed on public roads.