A system and method for aircraft performance predictions for climb flight phase is disclosed. In one embodiment, a method of aircraft performance predictions for climb flight phase in a flight management system (FMS) includes determining current predicted aircraft state using a total energy of the aircraft. Further, excess energy available in an engine of the aircraft is computed. Furthermore, a change of speed of the aircraft is computed at a given point in the climb flight phase. Kinetic energy (KE) change required is then computed for the computed speed change. Remaining energy available is then computed based on the computed KE change. The aircraft performance predictions for the climb flight phase are then computed using the determined current predicted aircraft state.