What is Load Shifting?

Legal Definition
Load Shifting is a dangerous phenomenon in water, air and even ground transportation. For a boat loaded with many small moveable items (for example, coal), if a boat begins to tip past 10 or 15 degrees consistently, some of the cargo will then spill on the downward side, and over time, this can lead to escalating tilt of the boat and eventual capsize. Such a dangerous occurrence is prevented by active load management, avoidance of high sea conditions, and proper container/bulkhead design.

On a cargo airplane, a professional loadmaster is necessary to prevent the highly-dangerous phenomenon of loadshifting. If a plane begins to take off with cargo unsecured, some of the cargo may slide to the aft of the airplane, resulting in catastrophic switch in centre-of-gravity and a stall condition. The National Airlines Flight 102 disaster is currently believed to be a result of load shifting.
-- Wikipedia
Legal Definition
Moving demand from daily peak hours to off-peak hours. A load management technique.