When you are uncoupling a trailer, you should lower the landing gear until:

It makes firm contact with the ground.. Section 6.4: Lower the landing gear until it makes firm contact with the ground.

When you are uncoupling a trailer, you should lower the landing gear until:

ANSWER BREAKDOWN
  • A. Incorrect. "It just touches the ground." is not correct. Lower the landing gear until it makes firm contact with the ground.
  • B. Correct. Lower the landing gear until it makes firm contact with the ground.
  • C. Incorrect. "It lifts the trailer off the fifth wheel." is not correct. Lower the landing gear until it makes firm contact with the ground.
  • D. Incorrect. "It is halfway down." is not correct. Lower the landing gear until it makes firm contact with the ground.