If the trailer wheels begin to skid and the trailer starts to swing out (trailer jackknife), what should the driver do?

TRAILER JACKKNIFE (trailer swings out): Occurs when the trailer wheels lock up and lose traction, causing the trailer to slide and swing out to the side. CORRECTION: RELEASE THE BRAKES — this allows the locked trailer wheels to start rolling again and regain traction; rolling wheels track straight, helping the trailer come back in line behind the tractor; locked (skidding) wheels have no directional control; PREVENTION: Brake smoothly and gradually; avoid hard braking, especially on slippery surfaces or in curves; brake before curves, not in them; keep the vehicle's speed appropriate for conditions; empty/lightly loaded trailers are MORE prone to wheel lockup and jackknife (less weight on the wheels); TRACTOR JACKKNIFE (drive wheels skid) is corrected similarly — release the brakes and steer to regain control; the counterintuitive but correct action for skid-induced jackknife is to STOP braking so the wheels can roll and regain traction; this is a critical safety concept for combination vehicle drivers.