Skidding downhill on black ice: survival tactics

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Greendrake

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#217952 19-Jul-2017 19:10

On last Friday night I crashed my beloved 1997 Prado after losing traction on black ice. The road was going down (like 7-10 degrees perhaps) and slightly turning right at the bottom of the hill. The speed was around 70-something (certainly not higher than 80) k, and the wheels were straight — I had not yet started turning them right. The vehicle suddenly started skidding down and left very quickly on all 4 wheels. I reflexively started braking but that was obviously helpless. In 2-3 seconds we were already going down the ditch on the left and rolling over. I had 2 passengers in there and, very very luckily, nobody got injured to the extent that the ambulance would advise hospitalisation. The truck was brilliant — it saved our lives, but lost its own (selling it for parts now).

Anyway, I've been thinking about that situation a lot and wondering if there was anything I could do once the skidding started. The vehicle was full-time 4WD, automatic. So, instead of braking, what if I:

Shifted to 2nd or even the low gear? This would've been painful to the automatic transmission, but would that help at all to get traction back, maybe in combination with any of the next options?
Applied gas? To make the wheels spinning and possibly "biting" through the ice into the road?
Turned the steering wheel right? Given that the vehicle was going down-left fast that would probably have caused rolling over on the left, BUT at least the vehicle would have rolled over on the road and not down the rocky ditch.
Anything else maybe?

By the way, here is a relevant topic on this forum (locked though). I am not even sure if 1997 Prado has any electronic stability controls, but by the looks that wouldn't have helped anyway.

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#1825441 19-Jul-2017 19:30

I spent a few years driving on winter roads in the Rockies.
Sometimes due to unavoidable circumstances you just have to hit the ditch (ie try and crash in as controlled a way as you can)

However given the right vehicle (and, esp tires) I've made it along roads you literally couldn't stand up on.

I wouldn't normally touch the brakes or apply gas. The trick is to 'feel' the grip your vehicle has on the road and try to prevent it breaking loose at all.
Electronic Stability controls have their place, but given that type of situation I'd have turned it off, slowed down and been super careful on downhill or off camber slopes.

Edit: I've also been in a couple of scary crashes including jackknifing and sliding a loaded truck & trailer down a Montana highway backwards in a blizzard

gbwelly

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#1825454 19-Jul-2017 19:34

Sounds like it was a done deal. Perhaps not applying the brakes you might have got away with it, depends if it was ice all the way to the edge of the road. Better not to keep wondering what you could/should/would have done, everyone came out ok.

Ge0rge

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#1825456 19-Jul-2017 19:39

gbwelly:
Sounds like it was a done deal. Perhaps not applying the brakes you might have got away with it, depends if it was ice all the way to the edge of the road. Better not to keep wondering what you could/should/would have done, everyone came out ok.

+1

In the 2-3 seconds you have described, it doesn't sound like there was very much to be done at all. Thankfully all came away ok (apart from the truck that is)

tdgeek

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#1825463 19-Jul-2017 19:53

I was raised on a farm, and while we didnt encounter black ice, we had rain wet clay on downhill tracks. No control, like black ice.

My advice is to not touch the brakes. Hold the wheel straight or let it go. There is no control, so you dont want to unexpectedly get a little grip and upset matters. The key is to allow the wheels to roll.

In your case, there will be grip at some point once your off the ice. You can dab the brakes softly to get a little bite before it locks. Best to do that and aim the wheel where there its least damage. Naturally, if we saw 10 different but similar instances each would vary a little. Your not concerned with saving it, so don't waste time on that, your concerned with trying to run into a fence or brush than a hard object. If its gong to end in a ditch, best to allow it to roll if you have any small amount of grip to enforce that, rather than hit it head on.

Batman

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#1825466 19-Jul-2017 20:03

The answer is NO.

When friction becomes zero, there's nothing you can do. Not even the computer can do anything. Can't beat physics.

You can change physics if you used snow tyres studded or studless, AND drive in a manner when friction > momentum

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#1825468 19-Jul-2017 20:05

Greendrake:

Anyway, I've been thinking about that situation a lot and wondering if there was anything I could do once the skidding started. The vehicle was full-time 4WD, automatic. So, instead of braking, what if I:

Shifted to 2nd or even the low gear? This would've been painful to the automatic transmission, but would that help at all to get traction back, maybe in combination with any of the next options?
Applied gas? To make the wheels spinning and possibly "biting" through the ice into the road?
Turned the steering wheel right? Given that the vehicle was going down-left fast that would probably have caused rolling over on the left, BUT at least the vehicle would have rolled over on the road and not down the rocky ditch.
Anything else maybe?

By the way, here is a relevant topic on this forum (locked though). I am not even sure if 1997 Prado has any electronic stability controls, but by the looks that wouldn't have helped anyway.

NO. nothing will happen ON THE ICE. if you don't touch the brakes, wait till the wheels cross the ice going straight, and when it grips something after the ice, start to slow down then.

If the corner is all the ICE, then there's nothing you can do.

Obviously if other cars had been ok it probably means you had one wheel on the ice when you braked, locking up the corner and throwing your car into a spin. So if you had not braked over the ice it might have been different. But hey, that's why it's called black ice right. In the ONE tyre on ice scenario snow tyres would have saved you.

Ge0rge

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#1825469 19-Jul-2017 20:06

Trouble is, in this case, the end of the ice was also the end of the road...

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#1825472 19-Jul-2017 20:09

Ge0rge: Trouble is, in this case, the end of the ice was also the end of the road...

I had updated my post. Yes I knew that.

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#1825473 19-Jul-2017 20:09

Watch some videos on snow tyres. (in short they're great under 10 C, not great over 10 C, which means really only works in Central Otago)

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#1825474 19-Jul-2017 20:11

Glad you're OK, by the way.

gzt

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#1825475 19-Jul-2017 20:13

Looks to me like you may have done a few things right and you were very lucky as well.

Is the area Google mapped and streetviewed?

Greendrake

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#1825478 19-Jul-2017 20:21

Thanks guys!

Is the area Google mapped and streetviewed?

It was the "Red Slip" spot on Milford Road, between Monkey Creek and Marion Corner. It is streetviewed indeed but the images are 5-year old and it looks differently now — rock falls and slips happen often there. I am planning to get there again at some point in near future to take more pictures — didn't have the chance much as the crash happened at night, and the next day I was there to recover the truck my phone battery was flat.

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#1825496 19-Jul-2017 20:39

It could be the perfect time to take one of those driving courses.

Aredwood

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#1825504 19-Jul-2017 20:57

Only thing that you could do is turn the wheels into the skid. And release the brakes. You might then be travelling sideways down the road. But it could be the difference between staying on the road, and managing to at least avoid a head on crash, or being able to choose where you will leave the road.

Changing down a gear wouldn't have helped. As there are a lot of 4WD systems that are in 2WD by default, and when they detect loss of traction via a big speed difference between front and back. Will then switch into 4WD mode. And the extra load on the tyres via the driveline could very easily cause you to skid if you haven't already. Also if the gearbox is electronically controlled,it will probably have the ability to override the gear that you select If the computer calculates that the engines max rated RPM would be exceeded. The Subaru 4EAT automatic gearbox released in the 80s could do that. So I would suspect that your Prado would have done so as well.

Azzura

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#1825506 19-Jul-2017 20:59

20yrs driving in Canadian winters ---- Not much ya can do on Black Ice.

Only thing that might have saved ya is a set of Blizzaks...perhaps studded winters would have helped. All seasons or summers pfffttt forget it! There is a huge difference in gripping power winters vs w/e else.

Honestly...i'd be pretty worried driving in snow conditions without some good studded winter tires. Blizzaks are suppose to be better than studded on ice.
i've driven all seasons in a few winters. But years and years ago I got a set of winter tires....and never used all seasons in winter again.

I doubt you could find Blizzaks in NZ. I've see winter tires on some farmers ute's and the holes for the studs.

Edit- What would I have done..

Downhill with a turn coming...pray for traction. I would've let off the gas and (if no ABS) pump the breaks as fast as I could. Perhaps also slowly turn (no sudden steering action) or edge my way to the side in hopes of getting off the black ice (if it was caused by other vehicles compressing down snow to a glaze of ice) to some/any kinda traction.

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