Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

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Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby 3WE » Fri Dec 01, 2017 12:23 am

Some foreign airline and one of those goofy high wing, 4-apu BAE-146 runs off the end of a sort of short runway at roughly 20 knots. ~Four die in post-crash fire :cry: (probably held up by someone grabbing a laptop) .

Analysis was interesting:

-6-knot downwind landing (within procedures and deemed not a factor).

-Spoilers do not deploy (report does not really get into WHY, it clearly indicates that they were selected by the crew) IMO, this is a major contributing factor, BUT data indicates that even with a tailwind AND no spoilers, a stop should be possible with more-than-adequate safety margins.

-Runway damp, but not wet (not deemed a major contributing factor ITSELF, again, scientific engineering says downwind, no-spoiler, damp runway still = a stop with plenty of buffer.)

THE critical factor...when the spoilers do not deploy, the crew becomes scared and feels deceleration is inadequate...so they select 'emergency brakes'

On this plane, 'emergency brakes' disables anti-lock braking and results in locked wheels and a marked increase in stopping distance (~70%)

In some conditions dampness + skidding invokes a freaky "steam-hydroplaning condition" further increasing the stopping distance (The color of skid marks and strange rubber fragments are consistent with this condition).

How to avoid this? Sure, Evan would think that they should be trained that 'emergency' disables the ABS and that stopping distances will be markedly increased (I'd agree).

Still, quite the chain of events and who'd of thunk it? Some credence to Not_Karl calling for general ban of airplanes.
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Not_Karl » Fri Dec 01, 2017 1:20 am

AVHerald and Wikipedia.
Some credence to Not_Karl calling for general ban of airplanes.
CONCUR.
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Gabriel » Sun Dec 03, 2017 11:31 pm

Let's see... so you land... spoilers would not deploy... due to the wing still producing a significant lift you don't have enough WOW (weight-on-wheels) and hence not enough braking action...

How can you increase WOW?

It is sad that no no-spoiler procedure was in place, taught or trained. There were many possible ways to avoid this accident even after the spoilers failed to deploy. Keep the maximum braking with antiskid, raise the flaps, and, of course, go around. I don't know which one is best and I don't care too much. The manufacturer should establish one and the airline should train the pilots on it.

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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Not_Karl » Mon Dec 04, 2017 6:07 am

How can you increase WOW?
Making all the passengers jump and hit the floor at the same time? 8-)
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby elaw » Mon Dec 04, 2017 11:43 am

How can you increase WOW?
Get pizza delivered? :mrgreen:

It seems to me the biggest single cause of the accident here was the pilot's selection of emergency braking. Everything seems to indicate that had he not moved that one lever to that one position, there would be nothing to discuss here.
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Gabriel » Mon Dec 04, 2017 7:49 pm

How can you increase WOW?
Get pizza delivered? :mrgreen:

It seems to me the biggest single cause of the accident here was the pilot's selection of emergency braking. Everything seems to indicate that had he not moved that one lever to that one position, there would be nothing to discuss here.
No, the biggest single cause was the failure of the spoilers, undoubtedly.
First of all, if the spoilers had deployed the plane would have stopped even if the pilot actuated the emergency brakes.
Second, the pilot would not have actuated the emergency brakes had the spoilers deployed.
Third, the pilot used the emergency brake because he had an emergency and needed to bake. What is the emergency brake there for if not for that?

And the way to increase the WOW, without increasing the mass (no point in doing that since the acceleration would be the same), is to decrease the WSEBOW (weight somewhere else but on wheels).

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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby 3WE » Mon Dec 04, 2017 9:48 pm

***It seems to me the biggest single cause of the accident here was the pilot's selection of emergency braking.***
***No, the biggest single cause was the failure of the spoilers, undoubtedly.***
Anyone read what each other says around here? (Ok, sometimes I read it inaccurately), but what did I say in the OP???? :evil:

According to the TV show, the selection of the emergency braking was the root cause.

They say that because scientific data and simulations indicated that the plane could have come to a full (and slightly fat, dumb and happy) stop even though there were no spoilers and even though there was a tail wind and even though there was moisture...

So...I see where they are technically correct.

As I said in my original post, I do have a hard time completely dismissing the spoilers...they were part of the sequence, and they do have a generally significant effect on stopping. :evil:

So...I get Gabby's point, but Ericie's point is correct- data indicate that a full stop was doable- even with some buffer.

Also, it was alluded to in the report- completely locking the brake can increase stopping distance by something like 70% (I find it amazing that it's that much).

If it really is that much, then maybe there should be a bit of type-specific training- Hey guys, emergency braking locks the wheels and can increase stopping distances by 70%....don't use it if you really have to stop (of course, why is it even termed 'emergency'...maybe it should be termed 'totally lock the brakes'...

(I recall Flyboy mentioning his autobrakes which if set to RTO would could have unpleasant effects on one's nose and forehead (depending on the exact location of the hard plastic of the service tray)...it seems that the automatic brakes here work differently).

...finally a stupid question...should it be easier to achieve maximum braking shouldn't the pilots be confident they are stomping on the brakes hard enough that selecting 'emergency' not really be necessary???
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Not_Karl » Tue Dec 05, 2017 2:02 am

***It seems to me the biggest single cause of the accident here was the pilot's selection of emergency braking.***
***No, the biggest single cause was the failure of the spoilers, undoubtedly.***
(...)According to the TV show, the selection of the emergency braking was the root cause.(...)
Wrong, the root cause was the decision to land. Had they Not_landed, the crash would not have happened, no matter what braking procedure was used or the behaviour of the spoilers.
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Gabriel » Tue Dec 05, 2017 2:33 am

***It seems to me the biggest single cause of the accident here was the pilot's selection of emergency braking.***
***No, the biggest single cause was the failure of the spoilers, undoubtedly.***
Anyone read what each other says around here? (Ok, sometimes I read it inaccurately), but what did I say in the OP???? :evil:

According to the TV show, the selection of the emergency braking was the root cause.

They say that because scientific data and simulations indicated that the plane could have come to a full (and slightly fat, dumb and happy) stop even though there were no spoilers and even though there was a tail wind and even though there was moisture...

So...I see where they are technically correct.

As I said in my original post, I do have a hard time completely dismissing the spoilers...they were part of the sequence, and they do have a generally significant effect on stopping. :evil:

So...I get Gabby's point, but Ericie's point is correct- data indicate that a full stop was doable- even with some buffer.

Also, it was alluded to in the report- completely locking the brake can increase stopping distance by something like 70% (I find it amazing that it's that much).

If it really is that much, then maybe there should be a bit of type-specific training- Hey guys, emergency braking locks the wheels and can increase stopping distances by 70%....don't use it if you really have to stop (of course, why is it even termed 'emergency'...maybe it should be termed 'totally lock the brakes'...

(I recall Flyboy mentioning his autobrakes which if set to RTO would could have unpleasant effects on one's nose and forehead (depending on the exact location of the hard plastic of the service tray)...it seems that the automatic brakes here work differently).

...finally a stupid question...should it be easier to achieve maximum braking shouldn't the pilots be confident they are stomping on the brakes hard enough that selecting 'emergency' not really be necessary???
Yes, I did read all of your posts. They said main cause was emergency brake and I don't agree for the reasons already explained.

They said it would have stopped with buffer even without spoilers had they not used emergency brake.
Did they say if they would have stopped with margin even using emergency brake, had the spoilers deployed? They didn't say it, right? But yes, they would have.

They said that the emergency brake factor may have increased the stopping distance by 70%. Did they say how much the distance was increased by the no-spoiler factor? Likely more than that (cue: the nose down made contact before than or together with the main gear, meaning that at about level attitude they had about lift = weight and WOW about zero, that multiplied by mu gives, zero).

So yes, I read your post, I understand what the Air Disasters show said, and I stand on my position.

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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby monchavo » Sun Dec 10, 2017 9:58 am

Chaps, this really has to stop. Reasonable, informed and sensible debate?! It's not 2007 you know! :)

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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby 3WE » Sun Dec 10, 2017 11:51 am

Chaps, this really has to stop. Reasonable, informed and sensible debate?! It's not 2007 you know! :)
Humor noted.

Similarly, I declare that you have offended my fragile persona and I shall start a Twitter campaign to boycott AD.info.

And, for the serious side, indeed...the 10? of us participant dinosaurs from that era indicates that times have moved on.
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby ocelot » Mon Dec 11, 2017 6:55 am

Arguments like these are (I originally wrote "why", but it's actually more like "how") causality is such a slippery subject when examined closely.
Besides, the pilot actions can't be taken as the root cause; clearly the pilots were set up to fail by having nothing on file for what to do if the spoilers don't.

According to the wikipedia page they tried S-turns as they got to the end of the runway. This makes me wonder: has anyone ever tried a "bootlegger reverse" under such conditions and gotten away with it?

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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby elaw » Mon Dec 11, 2017 11:37 am

Besides, the pilot actions can't be taken as the root cause; clearly the pilots were set up to fail by having nothing on file for what to do if the spoilers don't.
Probably true, but I'll bet dollars to doughnuts (because both are cheap) that they *were* trained that selecting "emergency braking" does not increase braking effect and could well decrease it. Although it's easy to understand why in a moment of panic, they might think the opposite.
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Gabriel » Mon Dec 11, 2017 12:19 pm

I'll bet dollars to doughnuts (because both are cheap) that they *were* trained that selecting "emergency braking" does not increase braking effect and could well decrease it. Although it's easy to understand why in a moment of panic, they might think the opposite.
Panic is not the only possible explanation. The braking effectiveness at the beginning of the landing roll was very likely very close to "zero": the plane touched down in a level pitch attitude, what means that at that attitude the lift was about the same than the weight which, without spoilers, will remain more or less the same with the plane at level pitch attitude on the ground, until it looses speed, and lift about equal to weight means about zero weight-on-wheels which in turn means about zero braking action. A perfectly calm and rational pilot, especially without a procedure and training for no-spoilers, may miss-diagnose the lack of braking action as a brakes failure (for example, he can think "spoilers didn't deploy, plane is not braking, what connects the two? Hydraulics!"). And what is the procedure for "brakes not working"? I don't know, but if it doesn't involve activating the emergency brakes, please explain what the emergency brakes are there for. "I know that emergency brakes locks the wheels and is less effective than normal brakes, but it is a lot better than no brakes".

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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby elaw » Mon Dec 11, 2017 1:34 pm

I see your point, but "almost no weight on the wheels" at the moment the plane touches down is a thing with every plane that doesn't have spoilers, including the ones you and I have flown! I suppose the difference is the 172 driver knows and expects that, and knows not to stand on the brakes the moment the wheels contact the ground. Whereas the pilot of an airliner would expect better braking at that time, although still not 100%.
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby 3WE » Mon Dec 11, 2017 11:34 pm

***A perfectly calm and rational pilot, especially without a procedure and training for no-spoilers, may miss-diagnose the lack of braking action as a brakes failure***
EXCEPT...

It seemed to be clearly established that the pilots promptly diagnosed that there were no spoilers.

I wish the TV show would have gotten more into what the stopping distance would be like BUT ADD IN THE HUMAN FACTORS PART...

Instead, the show seemed to say, "Scientific engineering said they would have stopped with adequate safety buffer" (almost in a dismissive tone), but then they go on to show the pilots as markedly concerned with the braking action before switching to emergency brake...

Is it more correct that "Scientific engineering said they would have stopped alright, but the safety buffer might not have included pilot underwear survival?..."

And, I go back to a comment earlier- shouldn't it have been clear that they were getting maximum braking from the pedals...a flashing red light indicating that ABS was kicking in? A buzzing pedal feedback just like I get in my Chevrolet Silverado? Something?

While I agree with Eric, that they I'd bet that they were sort of trained...it sorta seems like it was not driven home that "emergency brake" is really gonna lock things down and is really gonna lengthen your stopping distance....

...and seems to beg the question, just what the hell is the purpose of emergency braking?...in case you land really hard and break your back and paralyze your legs, you can still twist a knob with your hand and stop? [Bobby would need blue font for the previous sentence.]
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Gabriel » Tue Dec 12, 2017 2:23 pm

***A perfectly calm and rational pilot, especially without a procedure and training for no-spoilers, may miss-diagnose the lack of braking action as a brakes failure***
EXCEPT...

It seemed to be clearly established that the pilots promptly diagnosed that there were no spoilers.
+#$^~@&^%#!!!!!!

Your asterisks are very convenient to mutilate my quote in the most suitable place to adjust it to your agenda, aren't they?
A perfectly calm and rational pilot, especially without a procedure and training for no-spoilers, may miss-diagnose the lack of braking action as a brakes failure (for example, he can think "spoilers didn't deploy, plane is not braking, what connects the two? Hydraulics!"). And what is the procedure for "brakes not working"? I don't know, but if it doesn't involve activating the emergency brakes, please explain what the emergency brakes are there for. "I know that emergency brakes locks the wheels and is less effective than normal brakes, but it is a lot better than no brakes".

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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Gabriel » Tue Dec 12, 2017 2:40 pm

Let me set the record straight:
  • Spoilers are a REQUIRED means of braking, as much as the brakes themselves. Airplane stopping performance is computed with the braking action generated by the weight-on-wheels after spoiling the lift with the spoilers. A landing in a perfectly legal (but marginally legal long) runway is guaranteed to overrun with no spoilers, as much as with no brakes.
  • So spoilers is a critical piece of equipment. You have a whole set of landing performance for abnormal landings with no spoilers.
    The spoilers should NEVER fail, as much as the brakes (or the elevator or... you get it)
  • Especially, they should never fail without previous warning. If you have an hydraulic failure you can plan ahead that you'll not have spoilers and choose a long enough runway.
  • In this case, the spoilers did fail.
  • The investigators didn't find the cause of the spoilers failure but identified 2 possible failure modes.
  • One of them was "2 microswitches in the thrust levers failed"
  • Except that the failure of the 1st microswitch would remain transparent and basically undetectable, because it would give no symptom. And it could remain like that for months or perhaps years (I don't know what maintenance check involves verifying the working conditions of each microswitch individually).
  • So basically we have a catastrophic single-point-of-failure.
  • The manufacturer, or the airline, had no procedure in place for unexpected "no spoilers" landing (the only rational procedure I can think of is go around)
  • The pilot identifies the no spoilers, identifies the no (or extremely low) braking action, and uses the emergency brake.
  • We blame the pilot for that, and don't request any safety action to the manufacturer for the critical failure of the spoilers in a critical phase of flight or for the lack of a procedure to handle that.
That's a way to advance safety and avoid recurrence!!!!

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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby 3WE » Tue Dec 12, 2017 7:28 pm

***A perfectly calm and rational pilot, especially without a procedure and training for no-spoilers, may miss-diagnose the lack of braking action as a brakes failure***
EXCEPT...

It seemed to be clearly established that the pilots promptly diagnosed that there were no spoilers.
+#$^~@&^%#!!!!!!

Your asterisks are very convenient to mutilate my quote in the most suitable place to adjust it to your agenda, aren't they?
You're over reacting a bit.

I am emphasizing that if the discussion is this crash, then the misdiagnosis of brake failure is not particularly valid.

If we are discussing a broader issue of design for a broad range of things, I acknowledge your statements.

ALSO...I would hope that after the spoilers were diagnosed, they would have some idea that they had SOME braking and that the lack, of PREFERRED braking action was a lack of "weight"...I also go a slightly different direction in saying shouldn't there be some good indication that the brakes are maxed and ABS is doing it's thing...

Unlike Evan, I am cool with you taking another direction...no agenda...just a reminder that for this crash, there was not a misdiagnosis.

Please, carry on and note the OTHER agreement on asking "just what emergencies are emergency brakes intended for".
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Gabriel » Tue Dec 12, 2017 8:14 pm

if the discussion is this crash, then the misdiagnosis of brake failure is not particularly valid. Just a reminder that for this crash, there was not a misdiagnosis.
Why not? What I was saying is that exactly the opposite is a possibility.

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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Not_Karl » Tue Dec 12, 2017 8:18 pm

Please, carry on and note the OTHER agreement on asking "just what emergencies are emergency brakes intended for".
For parking, like in cars.
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby 3WE » Tue Dec 12, 2017 8:52 pm

Please, carry on and note the OTHER agreement on asking "just what emergencies are emergency brakes intended for".
For parking, like in cars.
As a teenager, I found the "emergency brake" to be much fun in snowy conditions.

The directional behavior of the car would go into 'alternate law'.

One might briefly ask, "What's it doing now?"

Of course, believers in engineering and physics tended to reply, "exactly what it is traditionally supposed to do."

As so often is the case, with a little study and practice time, one could maintain a reasonable amount of control and avoid total disasters, while dealing with the alternate law, even though controllability was somewhat reduced.
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby 3WE » Tue Dec 12, 2017 10:14 pm

if the discussion is this crash, then the misdiagnosis of brake failure is not particularly valid. Just a reminder that for this crash, there was not a misdiagnosis.
Why not? What I was saying is that exactly the opposite is a possibility.
Ok...two possibilities here.

A. The pilots thought they had no brakes (thinking they failed WITH the spoilers) and hoped that the emergency brake would fix it.

B. The pilots thought they had brakes, but that emergency would give them more braking.

My thought was that they would most likely sense the brake application and think that the brakes were probably working, but working crappy from limited WOW- this seems to be common knowledge among us ass-hats, I ass-ume the professionals generally know it too.

Your thought is that maybe they thought the brakes weren't working.

I guess we will have to read the final report to learn what they were thinking- right now I don't think we know exactly what the crew was thinking.

I concur that a no-spoilers procedure seems like a good idea to we outsiders.

I would hope that we concur that, ideally, it would be nice to try to train them that 'emergency' brakes = locked wheels and marked increases in stopping distances...so there would be less thinking and more knowing.

I would also hope that we concur that the unexplained spoiler failure is A weird and B a significant contributing factor.

I do not_concur that this crash is pilot error (nor concur that the pilots were blamed as such)...I tend to blame "system error", and think the emergency brake application was valid attempt to 'save the day', and that the significant effect on stopping distance was not known.

Now, what is your agenda?
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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby Gabriel » Tue Dec 12, 2017 11:56 pm

Now, what is your agenda?
That a critical flight control had a 100% total failure, that the cause for that failure was not identified, that a possible failure mode identified a catastrophic single point of failure, that no safety action was requested because of this failure, that this failure CAUSED the accident, and that some people is demoting this CAUSE to a FACTOR.

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Re: Smithsonian Channel Air Disasters- Atlantic Airways 670, BAE 146 Overrun.

Postby 3WE » Wed Dec 13, 2017 12:58 am

Gabby/3BS weaving:

Ok man, but you still need a good, stiff adult beverage

Now, what is your agenda?


That a critical flight control had a 100% total failure, that the cause for that failure was not identified, that a possible failure mode identified a catastrophic single point of failure,

Yes, the TV show indicated that the fire was pretty bad...which may have made it next to impossible to determine the cause...I note your comment that from the arm chair and 'what's on paper' that maybe the throttle interlock switches are not as fail safe as "we" outsiders would like.

that no safety action was requested because of this failure,

Don't sense too much disagreement from the membership here- please repost there if you want Evan's take.

that this failure CAUSED the accident, and that some people is demoting this CAUSE to a FACTOR.

Back to post #1...I agree that the spoilers contribution seemed a bit too minimized in the TV version...and, agree, they would have increased the stopping distance (we have AA, Little Rock to learn about spoilers and brakes and reverse...and the steam-hydroplaning seemed to be a freakish condition that contributed...

That being said, there's maybe some gray-area nuances that need to be considered...Eric believes there may have been training to not use emergency brakes...what if the deceleration was actually going OK with ABS, but after a significant delay emergency brakes were selected...what if there was some sort of notable tactile feedback that the ABS was working...again, I'm not an ATP, but my auto transport person license and recurrent training stressed that locking the wheels = less stopping ability while ABS = near-optimum stopping ability...and I am surprised that a sort-of sophisticated 4-engine jet would disable ABS without it being in plain, placarded language on the brake selector (and without some sort of clearly-marked full-braking+ABS setting
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