Hazards, Emergencies & Skid Control

5 free sample questions of the 40 in this topic. The full set is in the app.

1. Question 1

   A skid happens whenever:

   • A.The tires lose their grip on the road
   • B.The engine over-revs
   • C.The trailer brakes engage first
   • D.The road curves sharply
   Show answer & explanation

   Answer: A. The tires lose their grip on the road

   Skid = lost tire grip, caused four ways: over-braking, over-steering, over-acceleration, or driving too fast for conditions.

   Source: California Commercial Driver Handbook (DL 650) — §2.19 — Skid control and recovery

2. Question 2

   Most SERIOUS skids result from:

   • A.Driving too fast for road conditions
   • B.Worn steering boxes
   • C.Cold tires
   • D.Strong crosswinds
   Show answer & explanation

   Answer: A. Driving too fast for road conditions

   Drivers who match speed to conditions don't have to over-brake or over-steer — the root cause of most serious skids is simply too much speed.

   Source: California Commercial Driver Handbook (DL 650) — §2.19 — Skid causes: driving too fast

3. Question 3

   By far the most common skid is:

   • A.Rear (drive) wheels losing traction from excessive braking or acceleration
   • B.Front-wheel washout in curves
   • C.All-wheel hydroplaning
   • D.Trailer-only slide
   Show answer & explanation

   Answer: A. Rear (drive) wheels losing traction from excessive braking or acceleration

   Drive-wheel skids top the list — rear wheels lose traction through over-braking or over-acceleration.

   Source: California Commercial Driver Handbook (DL 650) — §2.19.1 — Drive-wheel skids

4. Question 4

   To stop an acceleration skid (drive wheels spinning on ice or snow):

   • A.Take your foot off the accelerator — and push in the clutch if it's very slippery
   • B.Brake firmly
   • C.Steer sharply against the spin
   • D.Apply the trailer hand valve
   Show answer & explanation

   Answer: A. Take your foot off the accelerator — and push in the clutch if it's very slippery

   Ease off the power; on very slippery surfaces also push the clutch in so the engine doesn't keep the wheels from rolling freely and regaining traction.

   Source: California Commercial Driver Handbook (DL 650) — §2.19.1 — Drive-wheel skids

5. Question 5

   Locked wheels are dangerous because:

   • A.They have less traction than rolling wheels — the rear slides sideways to 'catch up' with the front
   • B.They overheat the bearings
   • C.They wear flat spots only
   • D.They disable ABS permanently
   Show answer & explanation

   Answer: A. They have less traction than rolling wheels — the rear slides sideways to 'catch up' with the front

   A locked wheel grips less than a rolling one; the locked rear end slews sideways trying to catch up with the front wheels — sideways slide in a straight truck, jackknife territory in a combination.

   Source: California Commercial Driver Handbook (DL 650) — §2.19.1 — Rear wheel braking skids

35 more Hazards, Emergencies & Skid Control questions are in the app, along with explanations and flashcards for every one.

OnRoute is an independent study aid based on the federal CDL standards (49 CFR Part 383), the FMCSA Entry-Level Driver Training theory curriculum (49 CFR Part 380 Appendix A), and related Federal Motor Carrier Safety Regulations. It is not affiliated with, endorsed by, or sponsored by the FMCSA, AAMVA, or any state driver licensing agency. CDL knowledge tests are administered by your state, and state-specific requirements may vary — always consult your state's CDL manual.