Airplanes should not do this. In the clip above, a Delta Airlines Boeing 737 tilts backward on its tail while parked at the gate. This slow-motion lift-off at the gate, no doubt to the shock of the ground operations team and any passengers on the plane. This seesaw is a rare occurrence for passenger jets; it’s more common for cargo aircraft.
Airlines employ load planners, who, as the name suggests, plan for the expected and actual load of the aircraft – the weight of the passengers, the amount of fuel, food on board, and cargo. Keeping weight and balance within limits is important for aircraft performance and safety, and that isn’t just true on the ground.
On some flights, particularly with lightly-loaded Boeing 737-900 and Dash-8 aircraft, the flight attendants will request that passengers move forward in the cabin and in some cases the airline dispatch team will request that ballast – sand bags or rubber planks – be loaded into the front cargo hold.
Collected and summarized from the source below by Minh Pham https://thepointsguy.com/news/airplanes-center-of-gravity/