According to Australian Forklift Training operators should always try and park their forklift on a flat surface. The parking brakes on most forklifts are only designed to prevent the forklift from moving on either a flat surface or a very slight incline.
If a forklift is left on a hill or slope, the parking brake should not be relied upon. When getting their forklift license, operators are expected to learn the following question from the current WorkCover theory exam:
Q: If your forklift must be parked on an inclined surface, what precaution would you take?
Answer: In addition to the normal parking procedures, chock the wheels of the forklift.
WorkCover recommend that if a forklift must be parked on an inclined surface, in addition to the normal parking procedure (handbrake on, forks flat on the ground) something is used to chock the wheels. Proper wheel chocks can be purchased from any good safety shop.
Companies having inclines on their worksite need to ensure that their operators know the correct way to park on one.