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A flight instructor teaches Tesla Autopilot

Papafox,

One topic that you didn't mention, but I'm most interested in hearing a experienced pilots view of is; How to deal with near instantaneous manual takeovers from autopilot from a quasi passenger roll.

From my perspective, and some of those I've talked with, there is a very abnormal feeling once you have let the autopilot system take over. This leaves the driver (PIC) physically a passenger, while still retaining the full responsibility for the actions of the car. In addition, the now driver-passenger may at any time be required to take immediate control of the vehicle for an emergency situation. This type of operation, and takeover are not something that auto drivers are taught to deal with. I imagine that these same types of driver-passenger rolls and immediate takeover requirements are standard for pilots. Are there training exercises, philosophies, and/or techniques that pilots are taught to handle these issues that you feel could/should carry over to driving the S with autopilot?

Thanks,

Peter
 

Papafox

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Excellent post. As a former CFI and developer of testing/instructional media I know your post took time and thought. I think Model S probably ought to have a type rating itself, with modules for controls, navigation, powertrain, and so on. Maybe many would not pay too much attention to the details (I recall fewer than half the people I trained for Lears, for example, wanted to learn the material) but the more people who do learn as much as they can the better off the Tesla community will be.

I remember a five minute instruction manual to learn how to start a first generation idrive BMW 750. We are definitely in a world that demand careful instruction, if not 'type ratings', to deal with many new cars, not only the Model S.

Younhave done us a service sir.

jbcarioca, thanks for the kind words. The parallels with aviation are significant with this product, and much can indeed be gained by drawing from our aviation backgrounds to structure the learning experience.

I admit to being a little jealous about that time you spent flying Lear jets and have a story that I think you'll like. When I was 13 years old, my buddy Raymond and I went to an air show and found a Lear 23 with the door open and nobody guarding the plane. Naturally, we both slipped into the cockpit, sat down, and went about figuring out what everything was. After quite some time, a large man entered the jet and I knew we were in trouble because I recognized the man from pictures in Flying magazine as Bill Lear himself. My curiosity overcame my fear and I said, "Mr. Lear, this is a beautiful jet you have here, but Raymond and I have a few questions for you." He answered our questions and then spent the next 20 minutes showing us all sorts of cool stuff about the jet "Boys, this jet has backup systems on top of backup systems." The three men in suits who came with him spent that time baking out in the sun while Mr. Lear shared this moment of joy with two aviation-enthralled boys.

- - - Updated - - -

Papafox,

One topic that you didn't mention, but I'm most interested in hearing a experienced pilots view of is; How to deal with near instantaneous manual takeovers from autopilot from a quasi passenger roll.

From my perspective, and some of those I've talked with, there is a very abnormal feeling once you have let the autopilot system take over. This leaves the driver (PIC) physically a passenger, while still retaining the full responsibility for the actions of the car. In addition, the now driver-passenger may at any time be required to take immediate control of the vehicle for an emergency situation. This type of operation, and takeover are not something that auto drivers are taught to deal with. I imagine that these same types of driver-passenger rolls and immediate takeover requirements are standard for pilots. Are there training exercises, philosophies, and/or techniques that pilots are taught to handle these issues that you feel could/should carry over to driving the S with autopilot?

Thanks,

Peter

Bluetinc, this is indeed an important concept. Let me ponder the idea for a day or so and then give it my best shot.
 
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Not having a Tesla, I have several questions/comments. First, forward and back are unclear. Is forward, when referring to moving a stalk, towards the driver or towards the front of the car? Pull/push or towards driver/away form driver seems clearer. Congratulations on avoiding this issue. Next, I am not sure I fully understand how the button on the end of the stalk is used. How is set vs. resume handled? Finally, does the pointer on the cruise control icon move to show when actual speeds are different forms he set speed or does the white arrow always point to the needle? Just nit picking.

I was surprised when test driving a car to find that AP worked fine with lane markings on only one side detected. The only time the car tried to exit was when following a car that took the exit combined with the lack of a right side stripe. Nice job Tesla.
 

Papafox

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Jan 12, 2013
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Not having a Tesla, I have several questions/comments. First, forward and back are unclear. Is forward, when referring to moving a stalk, towards the driver or towards the front of the car? Pull/push or towards driver/away form driver seems clearer. Congratulations on avoiding this issue. Next, I am not sure I fully understand how the button on the end of the stalk is used. How is set vs. resume handled? Finally, does the pointer on the cruise control icon move to show when actual speeds are different forms he set speed or does the white arrow always point to the needle? Just nit picking.

I was surprised when test driving a car to find that AP worked fine with lane markings on only one side detected. The only time the car tried to exit was when following a car that took the exit combined with the lack of a right side stripe. Nice job Tesla.

SR22pilot, nit picking is encouraged here. When I talk about movement of the autopilot stalk, "forward" refers to away from the driver, towards the front of the car. "Back" is towards the driver. I will clarify in the top post.
 

Papafox

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Jan 12, 2013
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Papafox,

One topic that you didn't mention, but I'm most interested in hearing a experienced pilots view of is; How to deal with near instantaneous manual takeovers from autopilot from a quasi passenger roll.

From my perspective, and some of those I've talked with, there is a very abnormal feeling once you have let the autopilot system take over. This leaves the driver (PIC) physically a passenger, while still retaining the full responsibility for the actions of the car. In addition, the now driver-passenger may at any time be required to take immediate control of the vehicle for an emergency situation. This type of operation, and takeover are not something that auto drivers are taught to deal with. I imagine that these same types of driver-passenger rolls and immediate takeover requirements are standard for pilots. Are there training exercises, philosophies, and/or techniques that pilots are taught to handle these issues that you feel could/should carry over to driving the S with autopilot?

Thanks,

Peter

Bluetinc,
I've put up my first shot at explaining my mindset of using AutoSteer and of overriding AutoSteer. I will likely modify it slightly as a few days pass. I hope this first attempt is helpful. If not, please let me know how better I could address the subject.

The added information in the first post is as follows:
Your internal autopilot vs. the Tesla autopilot
Chances are that you've been driving for many years and you've grown quite comfortable with cruising the highways. Once you're underway, you hardly have to think about certain driving actions such as staying in the lane because they are now almost subconscious. That's your internal autopilot at work! If there's a huge semi-truck with Roman gladiator spikes whirling around each tractor wheelcap, your internal autopilot favors the other side of the lane as you glide by. Way to go internal autopilot! Now, we're asking you to forego the familiarity of this old friend of yours for a mechanized autopilot built into your Tesla. Here's one way to view this transition.

Rather than regarding the Tesla Autopilot as a machine that has taken over the driving duties, I suggest looking at the autopilot as if it had human attributes. Is it the pilot now and you're just a passenger? Hardly! You remain the captain and the Tesla autopilot is merely your copilot, and a rather inexperienced one at that. Initially, you will allow it to drive the Tesla when conditions are easy and its performance is predictably good. As it proves itself and as your confidence increases, you will allow it to drive during more difficult situations (steeper turns, more traffic, less-clear lane markings, etc.).

Eventually, you will find the need to override the autopilot. It is just a youngster, still learning (beta version). Fortunately, you have already practiced disconnecting the AutoSteer function by turning the steering wheel a bit or by pushing the disconnect button. You need to come to the opinion of what boundaries you will allow AutoSteer to work within. The boundaries you establish will vary with conditions. For example, a lane with a four foot shoulder to the left has a different boundary than a lane with a concrete divider 6 inches from the lane's edge. When you reach your limit of what you consider safe and comfortable, take over the steering manually by turning the wheel as needed to re-establish a comfortable drive. The good news is that your copilot has fabulous powers of concentration, and as he learns he will continue to improve and may one day save your bacon while you are distracted at a critical moment. No matter who is steering, however, remember that you remain the captain and retain responsibility for the safety of the operation.

Here's an important tip about taking over control from the autopilot. When you have a reasonable amount of wiggle-room in the event that AutoSteer fails to perform as needed, you will have time to comfortably get the Tesla back into the center of the lane if something goes wrong. Consider, for example, cruising along in the middle lane when there's no traffic. Yawn, the recovery is easy in such conditions. Now consider that you're driving a winding mountain road with a concrete center divider 6 inches from the left side of the lane you're in. In such cases, your brain needs to be already engaged and carefully plotting how close to that concrete you will ever allow your beautiful Tesla to drift and how you will take over and re-position the vehicle in the event of manual intervention. There's simply not enough time for you to elegantly recover from an error in such a situation unless your mind is already focused on the task. Thus, you focus carefully on the driving when there's little room for error, and you allow yourself to let down some of your guard at other times.
 
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J

jbcarioca

Guest
Papafox;1237763... When I was 13 years old said:
Flying[/I] magazine as Bill Lear himself. My curiosity overcame my fear and I said, "Mr. Lear, this is a beautiful jet you have here, but Raymond and I have a few questions for you." He answered our questions and then spent the next 20 minutes showing us all sorts of cool stuff about the jet "Boys, this jet has backup systems on top of backup systems." The three men in suits who came with him spent that time baking out in the sun while Mr. Lear shared this moment of joy with two aviation-enthralled boys...
.
Great story! There is a cautionary parallel between the LR23 and the Tesla AP. When the Lear 23 was introduced it had far higher performance than any other civil aircraft (it was derived from a fighter design-no surprise). Type ratings did not exist then so pilots with Airpane Multi-engine ratings could and did jump in, fire it up and promptly kill themselves. A couple years later the modern type rating system was devised, in recognition that there were aircraft so different that they demanded special qualifications.

Our Tesla's with AP could become a similar tale if people continue to behave irresponsibly, and ignore the training we all need to manage these vehicles appropriately. It might be more likely that outright prohibitions could happen. Either way your CFI approach makes very good sense to me.
 

bmah

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Papafox, thanks for the latest "installment" on your autopilot posting. I really think this article will help to convey the proper (safe) mindset to people taking advantage of this feature.

One thing that has long impressed me about aviators (good ones anyway!) is their mindfulness, particularly about their vehicle. I remember reading more than a couple of books about learning to fly that went into quite a bit of detail about the workings of a typical GA aircraft before ever talking about controls, procedures, and so forth. This emphasis on systems knowledge puzzled me at first, but it makes sense that if you know your vehicle better, you know its limitations (and capabilities), and how to be safe within those situations. (Contrast this with the "just hop in and hit the gas" mentality that many drivers have today.)

The safety benefits of knowing your vehicle well hold true for both cars and airplanes, but two Tesla examples that I've been thinking about lately (one is even relevant to the topic of this thread):

1. Knowing how the autopilot system uses sensor inputs makes you cognizant of situations where it'll work well and where it won't. One of my drives includes a freeway segment with a climbing turn into the sun, and this combination makes the lane markings hard to see (for SF Bay Area residents, this is eastbound Hwy 24, the right-hand bend approaching the Hwy 13 interchange, about 0830-0900). I know the autopilot system uses a visual light camera to determine where the lane boundaries are, and so if I have trouble seeing the lane markings, the Tesla probably will have problems with it too. (It did indeed, the one time I tried it, but I was expecting this to not work, so I was safe and in control the whole time even when the car tried to steer into another lane on its own. Curiosity satisfied, won't try that again.)

2. Regen limited by cold weather and resultant change in deceleration behavior. There's (almost?) no parallel for this in the ICE cars that most of us have experience with. But by being familiar with the Model S power/drive systems and how they work, you know to expect weaker regen, and prepare to use your friction brakes more.

In many ways those of us who are not aviators would do well to take cues from those who are. Thanks to you and other contributors for helping to educate us!

Bruce
(Not a pilot, but wishing I was.)
 

Papafox

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Jan 12, 2013
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Papafox, thanks for the latest "installment" on your autopilot posting. I really think this article will help to convey the proper (safe) mindset to people taking advantage of this feature.

One thing that has long impressed me about aviators (good ones anyway!) is their mindfulness, particularly about their vehicle. I remember reading more than a couple of books about learning to fly that went into quite a bit of detail about the workings of a typical GA aircraft before ever talking about controls, procedures, and so forth. This emphasis on systems knowledge puzzled me at first, but it makes sense that if you know your vehicle better, you know its limitations (and capabilities), and how to be safe within those situations. (Contrast this with the "just hop in and hit the gas" mentality that many drivers have today.)

The safety benefits of knowing your vehicle well hold true for both cars and airplanes, but two Tesla examples that I've been thinking about lately (one is even relevant to the topic of this thread):

1. Knowing how the autopilot system uses sensor inputs makes you cognizant of situations where it'll work well and where it won't. One of my drives includes a freeway segment with a climbing turn into the sun, and this combination makes the lane markings hard to see (for SF Bay Area residents, this is eastbound Hwy 24, the right-hand bend approaching the Hwy 13 interchange, about 0830-0900). I know the autopilot system uses a visual light camera to determine where the lane boundaries are, and so if I have trouble seeing the lane markings, the Tesla probably will have problems with it too. (It did indeed, the one time I tried it, but I was expecting this to not work, so I was safe and in control the whole time even when the car tried to steer into another lane on its own. Curiosity satisfied, won't try that again.)

2. Regen limited by cold weather and resultant change in deceleration behavior. There's (almost?) no parallel for this in the ICE cars that most of us have experience with. But by being familiar with the Model S power/drive systems and how they work, you know to expect weaker regen, and prepare to use your friction brakes more.

In many ways those of us who are not aviators would do well to take cues from those who are. Thanks to you and other contributors for helping to educate us!

Bruce
(Not a pilot, but wishing I was.)

Bmah,
If you ever chose to become a pilot I bet you'd be a good one. You possess a great mindset. Fortunately, that way of looking at the world will also help you be a better Tesla driver.

Yes, glare is one of the things that Tesla mentioned as possibly detrimental to AutoSteer functionality. It will be interesting to see just how much help we get from the database of info that Tesla is now collecting from Autopilot-equipped cars so that the database of road information can supplement the visual pictures from the sensors. In the meantime, stay focused with any situation of this type and thanks for mentioning it here!

I'll be doing my first winter driving in a Tesla within three or four weeks, and I'll be able to experience what you're talking about with regen being limited by cold weather (we don't have much of that here in Hawaii). I'll be looking for it.
 
The most important thing about automation, whether in an airplane or a car, is knowing when to use it and when not to use it. The airlines are moving more and more to automation policies which involve moving up or down a level of automation, and when it's appropriate to do so. Many times, even though autopilot can work, it's not wise or best to use it.

Incidentally, I loved the story about Bill Lear (I have many hours in Learjets). My understanding was that he always viewed all Learjets as belonging to him, no matter whose name was on the registration! And, of course, before Learjet he was a pioneer in the field of autopilots.
 
SUGGESTIONS FOR LEARNING AUTOPILOT IN STEPS.

garygid (Hot Air Balloon Commercial Pilot and Instructor rating)

It is probably wiser, and even safer, to Master each step before continuing
to the next step. Each step has its own desireable skill set, including both
observational and operational techniques, and situational limitations.

This procedure might not be for everybody, but some have found
it to be a good suggestion, so I share it with you.

Note that the AutoPilot (AP) functions are not programmed to
handle intersections, cross traffic, signal lights, stop signs,
human directions (like in construction areas), pedestrians, and
all manner of street and city situations. At this point (revision 2.7.56),
AP is intended for use on well-divided, limited-access, not-to-curvy
highways with very suitably and well painted lane markings
or edges on both sides of the lane. Still, there are many situations
of weather, sun or shadow, dirt, rain, snow, fog, etc. that it cannot
handle well. True, some people are trying these functions
"in town" or on non-limited-access roads, but I suggest that you
avoid this temptation, at least until you have become an
expert in recognizing and handling the "tricky" AP situations.

AP, as it is now, is intended for use AFTER the onramp and
merge into a suitable lane of traffic, up to BEFORE you begin
to slow for an exit or freeway interchange. However, the AP
does quite a remarkably good job in the many, many miles of
situations that it can recognize, and handle, properly.

1. Normal driving skills as applied to the Tesla.
Accelerating and slowing, stopping quickly and gently, steering
and parking ... all these are a bit different with a heavy vehicle.
If you are not completely comfortable with these, perhaps
best to not try AutoPilot (AP) until you get more experience.
However, enable the crash warning, setting it to "Early".
My wife still needs to master this step, as a first-time Tesla driver.

2. Lane Departure Warning
Get familiar with how the car detects Lanes, compared to
what you see as lane markings. This is suggested so that
you can better understand where the AP has difficulty with
lane detection, and can better anticipate the situations
where you will need to retake control from AP.
You will probably gain observational skills in seeing
different kinds of lane edge markings, and (optionally)
develop the steering skills to stay in lanes, and notice the
speed control needed to safely navigate lanes of all types.
You will be better able to answer "Why did the AP do that?".

3. Learn Concepts of normal Cruise Control (CC)
Turning On and Off, Activating, speed setting, speed increase
and decrease, Deactivating, and resuming manual speed control
should all become familiar concepts. With typical "normal" CC you
can crash right into something ahead. Note that a Tesla with active
AutoPilot (AP) functions does not allow "normal" CC operation.

4. Traffic Aware Cruise Control (TACC)
Using the "CC" in the AP Tesla is very much like normal CC, except
the car will try to detect a vehicle ahead of you, in your lane, and slow
down, if necessary to maintain a suitable following gap, which
shortens as speed decreases, and lenghtens as speed increases.
The settings are something like half-second intervals, from 1 (the
closest) to 7 (the longest gap). I recommend 7, at least for learning.
Learn how the car handles getting close, and what happens as cars
cut in or across in front of you. Also learn well what happens when
the car in front of you exits your lane.

The TACC has evolved over the last 8 months to be rather good
about what it was intended to do. Future improvements are likely
to be able to slow for curves ahead.

Note that the current TACC (in revision 2.7.56) does NOT slow for curves,
interchange lanes, exit lanes or curves, etc. Learn well the several situations
where you need to disable TACC and take over manual speed control.
These include traffic merging into your lane, stopped traffic or obstructions
ahead, or you merging into other traffic (the TACC is not yet programmed
to handle these situations). Be able to recognize and handle them all.

5. Auto-Steering (AS)
This is the latest AP addition: Steering in a sufficiently well-marked lane,
lane edges or boundries well defined, with TACC automatically enabled
for the in-lane speed control. Only gentle curves, and only when taken
at suitably slow speeds. It is a first release, a Beta version, which a wise
person would use with extreme caution, intently aware of the highway,
markings, traffic, etc. and always prepared to not only take control, but
to inhibit any error that the AS might be starting to make.

Of course, some might try to blame the car or Tesla when they crash.
Perhaps these folks were not "sufficiently wise".

Note that to achieve this overriding of the AP, when required or prudent,
the driver must at least be feeling the little twitches of the steering wheel,
in addition to being intently aware of the road situation. A tiny twich the
wrong way, be prepared to stop the motion of the steering wheel, and
resume control. Feeling the "twiches" lets you learn what AS is trying
to do, and have a much better chance of catching it before the car
moves very much in some unexpected manner.

So, avoid watching the car and the lane on the dashboard, and be
more than normally aware of the road and traffic situation, perhaps
even looking forward more than in normal driving for situations that
the AS or TACC cannot handle well. As your skills get better, you
will be able to relax more, but it is likely that you will have become
a much more aware driver.

Note: Step 5 is too much stress for my wife, at least at the moment.

6. Assisted "Auto" Lane Changing
Leave this until you can easily handle the Beta AS limitations,
then try it first on good lanes with no other traffic around.
Gradually learn what it does, making sure that the lane-changing
is safe to attempt, and how to regain control when necessary.

----------
Notes:

Step 2 is included primarily so you can become familiar with how the
car is seeing the lane markings, while you are still in total control.

Later, AP will use those perceived lane markings to try to drive your car.
You might be better at recognizing situations where AP will have trouble.

Such is my thinking, cheers, Gary.
 
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Papafox

Well-Known Member
Supporting Member
Jan 12, 2013
5,465
76,628
The most important thing about automation, whether in an airplane or a car, is knowing when to use it and when not to use it. The airlines are moving more and more to automation policies which involve moving up or down a level of automation, and when it's appropriate to do so. Many times, even though autopilot can work, it's not wise or best to use it.

Incidentally, I loved the story about Bill Lear (I have many hours in Learjets). My understanding was that he always viewed all Learjets as belonging to him, no matter whose name was on the registration! And, of course, before Learjet he was a pioneer in the field of autopilots.

donv, you mention something important here about when to use various levels of automation. One way of looking at things is that there are three levels of automation in the Tesla:
1) manually controlling speed and steering,
2) letting TACC (Traffic Aware Cruise Control) control speed while you control steering, and finally
3) allowing the combination of TACC and AutoSteer to control both speed and steering.

A reasonable plan is to downgrade to automation level 1 (manually control everything) when you find yourself in a tight spot and have to act quickly. You're already very competent with these skills and you can respond quickly to threats. Once you've sorted out the problems, you may wish to work yourself back up to automation level 2: TACC. With cruise control in charge of speed, you have offloaded a chore to the autopilot and your job of driving has just become easier. With cruise control performing well and conditions that are suitable, engage AutoSteer and return to full automation (Level 3), if desired.

On the other hand, if AutoSteer is the only issue, you may want to just turn the wheel enough to disconnect AutoSteer and allow Traffic Aware Cruise Control to keep doing what it is doing well. In such a situation, you have merely downgrowded from automation level 3 to automation level 2.

Ok, you've twisted my arm, so I'll tell another Lear story. Decades after Raymond and I snuck into Bill Lear's jet, I had the opportunity to meet Bill Lear's wife, Moya Lear at their property beside the Truckee River, west of Reno. When I told her the story of being caught red-handed in the Lear 23 cockpit, she gave a big smile and said, "So, you're the one!" Apparently the story of us sneaky 13 year olds made its way to the Lear dinner table that evening so long ago. When Moya passed away years after that, a formation of Lears, all with big wingtanks, flew low over the facility, when one of the planes went full-throttle and pulled up into the most beautiful missing man climb I've ever seen. I was awed by the performance and it was quite an emotion-stirring sight.
 
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Papafox

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Supporting Member
Jan 12, 2013
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76,628
Garygid,
Thanks much for sharing this well-thought-out orientation to using the autopilot system in a Tesla. I especially liked the comment about not looking at the image of the Tesla car below your speedometer and instead keeping your eyes outside the car.

My 70D is autopilot-equipped and my 40 is not, so I have experience using both the Traffic Aware Cruise Control on the 70D and the Cruise Control that is on the Model S 40. Is there a way to get the speed control on the autopilot-equipped cars to function in just standard Cruise Control mode? My 70D has always been traffic aware when cruise control is turned on.

Also, we ought to mention auto-braking, as well. This dramatic video shows a Seattle Uber car that is saved from an accident by the Tesla's automation systems. The website says the Tesla in the video was on autopilot when the Tesla prevented hte accident, but my understanding is that autopilot need not be turned on for auto-brake to function in autopilot-equipped Teslas. So, even when we're in the lowest automation level (manual steering and speed control), auto-brake is still watching out for us. If someone understands differently, please speak up.
 
Teslas with AP hardware activated (paid for) have TACC and no access to the old CC,
primarily because the TACC is considered safer than just plain CC, I suspect.

However, the TACC in 2.7.56 still has a weakness: it could unexpectedly speed up or slow down
during merging, accidentally blocking the vehicle that is merging. Since this can be a very
dangerous situation, I strongly recommend adjusting speed manually during the merge,
even if that requires turning off the TACC, in anticipation of the merge situation.

- - - Updated - - -

A Tesla with AutoPilot hardware, even if not "activated" by purchase (giving you
the TACC instead of CC, and the Auto-Steering Beta), uses the hardware to
provide some of these significant new safety features (not sure which ones):

1. Imminent Crash Mitigation - abrupt emergency braking (fairly sure)
2. Collision Warning - beeps to warn you, I use the "Early" setting. (think so)
3. Side or Blind Spot Collision Warning (maybe)
4. Better Proximity Warnings (believe so)
5. Lane Departure Warning - drunk-bump sounds, and feel? (think so)

So, you are given the more-safety hardware, and need to pay to activate
the driver-convenience features, but you get a safer Tesla. Thanks EM.
 
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I don't intentionally use TACC while I'm merging, but it's not at all unusual to have people merging in with me while TACC (and auto-steer, for that matter) are engaged. It seems to generally handle that situation very well.

I wish Tesla provided a way to disable auto-steer only without also disabling TACC (other than moving the steering wheel, which I don't like). Pushing away on the cruise control stalk, maybe, or pressing the button on the end. Right now, both do exactly the same thing-- disable both.

However, the TACC in 2.7.56 still has a weakness: it could unexpectedly speed up or slow down
during merging, accidentally blocking the vehicle that is merging. Since this can be a very
dangerous situation, I strongly recommend adjusting speed manually during the merge,
even if that requires turning off the TACC, in anticipation of the merge situation.
 
Understanding the TACC in lane-merging (two lanes become one lane):

This is not the case of a car in an adjacent lane moving into,
or through, your lane. In lane-merging, one lane is disappearing,
and the at-speed merging is required and urgent.

Under TACC, the speed of your car is controlled by 3 things:
1. The CC maximum speed setting,
2. The accelerator pedal can increase speeds,
3. The speed of the vehicle in front, if any.

As other traffic, for example at an on-ramp to the freeway, tries to merge with your car,
it might speed up to merge in front of you, or slow down to merge behind you, which
is often well accomplished if your vehicle maintains a constant speed. That would
be considered Passive Merging, where you do not facilitate the merging process.
In light traffic this method is often effective, especially when the merging traffic
has sufficient space to match velocities.

Often there are situations where it is wise, and safer, to help facilitate the merging
by speeding up to leave a bigger gap behind you, or slowing down to provide
more space in front if you - that would be Cooperative Merging.

The third case might be called Road Rage Merging, where you speed up as the
merging car speeds up, or slow down as the merging car slows down, essentially
blocking the merge - a very agressive and dangerous interaction, that most
of us try to avoid.

Unfortunately, with the TACC in control, just as the merging car accelerates to
nicely merge in front of you, the car in front of you might change lanes leaving
clear space in front of you (or just speed up), and your car can then suddenly
speed up and, being unaware of the merging situation, "block" the merge.
Similar situation with your car suddenly slowing down due to the unexpected
actions of other vehicles, over which you have no control.

To avoid the consequences of this possible, but unexpexted, "merge unfriendly"
behavior, I suggest using manual speed control, at least until TACC becomes
sufficiently "merge aware", in all your merging situations ... for safety.

Cheers, Gary
 
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