Aircraft weight:

Aircraft weight is a chief factor in airplane creation and operation, and it demands respect from all pilots and particular carefulness by all A&P mechanics and repairmen.
Extreme aircraft weight reduces the competence of an aircraft and the safety margin available if an emergency situation should arise. When an aircraft is designed, its aircraft weight is made as light as the necessary structural strength will allow, and the wings or rotors are considered to support the maximum allowable aircraft weight. When the aircraft weight is increased, the wings or rotors must produce extra lift and the structure must hold not only the additional static loads, but also the dynamic loads forced by flight maneuvers.

Most modern aircraft are so designed that if all seats are full, all baggage allowed by the baggage compartment is carried, and all of the fuel tanks are full, the aircraft weight will be grossly overloaded. This type of design requires the pilot to give great thought to the aircraft weight. If greatest range is required, occupants or luggage must be left behind due to over aircraft weight. If the maximum load must be carried, the range, dictated by the amount of fuel on board, must be reduced.

Some of the problems caused by overloading aircraft weights are the aircraft will need a top takeoff speed. Both the rate and angle of climb will be reduced if there is an aircraft weight problem. Due to over aircraft weight, the service ceiling will be lowered. The cruising pace will be also be reduced due to over aircraft weight. This will also cause the cruising range to be shortened. Maneuverability will be decreased due to extreme aircraft weight. A longer landing roll will be required because the landing speed will be higher. Excessive loads will be forced on the structure, especially the landing gear.