As
Checkboard says:
Fwd C of G limit: Manoeuvrability considerations
Aft C of G limit: Stability considerations
The C of G limits applied to the aircraft, during loading on the ground, also have to cater for all likely movements of the C of G and also the C of P in flight. For example:
- The C of G can move in flight as a result of fuel usage, fuel transfer, fuel jettison, mid-air refuelling, passenger movement, weapon release, water dropping or parachute dropping.
- The C of P can move in flight as a result of a change in aircraft speed, flap selection or altered wing sweep.
Mechanics of Flight by
A C Kermode (ISBN 0-273-31623-0) is worth reading should you wish to know more.