Forklift truck and method of operating the same

A forklift truck that is configured for placing on a first load a second load, comprising:

• a pair of forks for holding the second load;
• an actuator for raising and lowering the forks;
• a two-dimensional rangefinder having an emitting source configured to emit a measurement wave in a downwardly inclined direction from above and toward the first load, the two-dimensional rangefinder being configured to measure a distance between the emitting source and a measurement point which is located on a surface of the first load and at which the measurement wave is incident;
• a mover device that is configured to move the two-dimensional rangefinder so that the measurement point moves in a longitudinal direction in which the first load and the forklift truck carrying the second load face each other;
• a calculator configured to calculate a longitudinal distance between the emitting source and the measurement point based on the distance measured by the two-dimensional rangefinder;
• and
• a determiner configured to determine that the first load is in a condition in which there is a level difference between a front part and a rear part of an upper surface of the first load, and the front part is higher than the rear part, when a variation in the longitudinal distance that is generated in response to a displacement of the two-dimensional rangefinder moved by the mover device exceeds an upper limit of a specified threshold range;
• wherein the upper limit of the specified threshold range is a value obtained by adding a margin to a displacement of the measurement point.