When a slide is detected, the brakes are released and reapplied at a lower pressure. This process is repeated until a braking level can be found that is supported by available adhesion. The ATC system is watching this and only gives the brake system a few seconds to get things under control. If the watch dog time times out, ATC panics and puts the train into open loop braking, usually locking up the wheels on the first few cars. On a rainy day a sharp TO will run with the lead truck brakes cut out, so after the ATC system slides all the wheels flat, the wheels under the cab will not be pounding for the rest of his shift.