Winter Driving Survival – How to avoid skidding

  • Published
  • By Lt. Col. Robert Garner
  • 341st Missile Wing Chief of Safety
MALMSTROM AIR FORCE BASE, Mont. --  Winter is almost here. One of the greatest hazards we have here in Montana is driving on icy roads. Roll overs and vehicle mishaps are one of the 20th Air Force commander's top concerns. So the purpose of this article is to help you understand the hazard and provide you some tips to deal with it. 

Why do we skid? 

From a physics standpoint ,your car will skid if the amount of force on your tires exceeds the amount of grip they have. Braking, accelerating and turning all apply force on your tires. Your tires and the contact patch they make on the ground have a finite amount of grip. This grip decreases when the roads get wet and, even more so when they get icy.

 In addition, the faster you go the more force is applied on your tires as you turn, accelerate or decelerate. Simply put, speed and ice decrease the amount of available traction you have. Turning, accelerating or braking use up that available traction. 

How does a skid develop?
Frequently skids don't just happen out of the blue. Usually people start driving in decent conditions, their car is reacting normally. Then the temperatures drop, precipitation increases and as temperatures drop below 32 degrees Fahrenheit, ice slowly starts to form. There can be variations on when the ice forms on terrain depending on changes in elevation, shadows from nearby mountains and a variety of other factors. Often people will find their cars start to react differently. As the traction decreases on the road, your car may need more steering input to turn. 

At a certain point, however, people may come up to a turn where their speed and the angle of the turn is such that their steering input causes them to exceed their available traction and they skid. Initially what typically happens is the car "pushes" out of the turn, the driver senses they are not turning enough and so they wind in more steering. Next they sense it's not working and instead of reducing their steering input and gradually coming off the accelerator to get weight on the front steering tires, they wind in even more steering as they start heading off the road. 

Finally, drivers may rip their foot off the accelerator and maybe even slam on the brakes. This last move causes the car to violently shift forward, weight comes off the back, and with the tires at the very limit of adhesion, the back starts coming around. Too late the driver starts rapidly winding the steering wheel in the opposite direction trying to steer into the skid, the car is now weighted to the front, the front tires may be griping, the back tires not so much. 

As the driver tries to steer back into the skid the rear tires violently swerve in the opposite direction. The driver can go through several cycles of this fishtail but inevitably the car swaps ends, goes off the road and if it's in the wrong orientation, can trip on the terrain and roll. This is one possible scenario. Skids can develop in different ways but this one is typical. 

How do we use this knowledge? 

It helps to understand a little bit how vehicles are engineered. When designing cars, engineers design them to drive primarily on clear dry roads and driving at the speed limit with a margin of safety. On a dry road, taction doesn't need to be managed much because the car is designed to perform all prudent maneuvers at the speed limit on dry roads. As the conditions deteriorate however, the car is no longer able to maneuver at the speed limit. 

This is when decisions need to be made. You have to choose how slow you have to go. And actually, you are precisely in the same situation as a race car driver driving a car at the limit of traction around a course. This is where your state of mind, training and motivation become vital. A race car driver drives at the very limit and edge of traction in these circumstances in order to win a race. They have a lot of things going for them. 

Pristine track conditions, a superbly engineered car checked out by a team of expert mechanics and engineers, and often years of training and experience. The other thing they have going for them is they are in a roll cage, five point harness, helmet and Head and Neck Support device. The final thing the race car driver has is that they only have to survive an afternoon race. Race car drivers can accept greater risk because the consequence has been managed. 

Most ordinary drivers are in a vehicle where the roof pillars are really not designed to sustain a roll over. Most driver's cars are not engineered to make maximum available use of all traction. Also most of the world's drivers, to succeed, have a lifetime of driving to get through. 

ICBM drivers can expect to have to complete more than 50,000 miles of driving, roughly two times the circumference of the globe, successfully to complete their "race." 

Despite these differences, many people are going to treat the situation where they are driving on slippery roads with the same attitude that a race car driver does. They will tend to drive as fast as they think they can without skidding, basically at the limit of traction. 

You may have experienced this. Perhaps you've heard the term, "white knuckle driving." White knuckle driving is where your vision is fixated, you're scared and you're griping the wheel tightly. It's essentially your body's way of telling you, you're driving too fast.
When you sense the car is not turning as efficiently as normal, first don't panic, violent moves at this point will initiate a skid. 

Second, find the next straight patch of road. While going straight, slow down gradually in a straight line, get down to a speed where you know, without a doubt, that you can make the next turn safely. From there on, drive well down in your comfort zone. 

Do all your braking in a straight line and slow down well before you have to maneuver. Ignore the NASCAR wanabe's behind you and drive at the right speed for your car and abilities. 

All 341st MW units are required to conduct skid and gravel training. If you would like more training, contact your unit Vehicle Control Officer or training office. Questions on skid and gravel training can be also be addressed to the 341st MW safety office at 731-6719.