Avoid cruise control, when wet or icy

I wonder how many people know about this?

A 36-year old female had an accident several weeks ago and totalled her car. A resident of Wollongong, NSW, she was travelling between Wollongong & Sydney.

It was raining, though not excessively, when her car suddenly began to hydroplane and literally flew through the air. She was not seriously injured but very stunned at the sudden occurrence!

When she explained to the policeman what had happened, he told her something that every driver should know – NEVER drive IN THE RAIN WITH YOUR CRUISE CONTROL ON.

She had thought she was being cautious by setting the cruise control and maintaining a safe consistent speed in the rain.

But the policeman told her that if the cruise control is on and your car begins to hydroplane — when your tyres lose contact with the pavement, your car will accelerate to a higher rate of speed and you take off like an airplane.

She told the policeman that was exactly what had occurred. The policeman estimated her car was actually travelling through the air at 10 to 15 kms per hour faster than the speed set on the cruise control.

The policeman said this warning should be listed, on the driver’s seat sun-visor – NEVER USE THE CRUISE CONTROL WHEN THE PAVEMENT IS WET OR ICY, along with the airbag warning.

Insurance companies, do warn about this

Pass it on to your family & friends

2 thoughts on “Avoid cruise control, when wet or icy

  1. Matt

    This is bullshit. For starters, if the drive wheels lose contact with the pavement, HOW can the car POSSIBLY accelerate since there is nothing to push the car forwards? Once the drive wheels lose contact with the pavement, the car will slow down. It’s physics. Wind resistance and friction with the water will slow the car down.

    The second part of the car “taking off like an airplane” is also tragically stupid. Airplanes take off because they have wings designed to lower the air pressure on the upper surface and create lift. The only wings on cars are at the rear and are mostly there for looks with no aerodynamic benefits. A few sports cars and aftermarket wings produce a lower air pressure on the bottom of the surface, causing down force. So…cars are not shaped to fly and don’t simply do so because they are hydroplaning. Race cars that simply “take off” are traveling at speeds close to 200 mph and are usually not pointing in the direction of travel at the time. The notion that the family SUV, sedan, or minivan could duplicate this is preposterous.

    But here IS what is happening that can cause drivers to lose contol on wet or icy roads with the cruise control on. The car detects the speed of the drive wheels and makes throttle adjustments to maintain that speed. Like if you are going down a hill, it will close the throttle. Conversely, if you are going up a hill, it will open the throttle to maintain speed.

    A steeper incline will cause the throttle to be opened greater. In cars with automatic transmissions, the transmission may downshift into a lower gear for a greater mechanical advantage.

    When a vehicle hits patch of standing or running water (not simply wet asphalt) it can cause a deceleration. The cruise control will open the throttle wider and wider until the set speed is resumed. If the change in speed is great enough, it could cause the cruise control to open the throttle completely causing a downshift in the transmission and a lot more power going to the drive wheels. If the wheels are already hydroplaning (rolling or gliding across the top of the water rather than the asphalt) they have little or no resistance due to the lack of traction causing the wheels to spin faster than the car is actually traveling. Wheel-spin results in less traction, and therefore less controlability of the vehicle. Furthermore, if one drive wheel comes into contact with asphalt before the other (especially in vehicles with limited slip differentials) it can cause a yawing effect as one wheel pushes that side of the vehicle forward faster than the other. In a vehicle equipped with front wheel drive, this could cause severe “torque steer” causing the front wheels to physically turn to the left or right if the driver does not have a firm grip on the steering wheel. If severe enough, this can cause top heavy vehicles like trucks, vans, and SUVs to roll over.

    This is less likely while simply cruising down the highway, but more possible when using the “Resume” or “Accel” feature on the cruise control to accelerate.

    Oh…and cars don’t “take off like an airplane” because it’s icy either.

  2. Milena

    Now on principle I never drive with the cruise control simply because Houston drivers are incredibly aggressive and there is no way to maintain a controlled distance on the highways when everyone is weaving in and out with just millimeters to spare between their car and yours. Still, I had no idea that cruise control could be dangerous when driving in the rain. This is the first time I ever heard of it. Thanks for the heads up.

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