Abstract: An onboard aircraft flight optimization system that includes an onboard performance management computer, a control display unit, an infrared probe, a temperature probe, a weather radar, an inertial navigation system, and comparing apparatus. The control display unit inputs a position remote from an aircraft into the performance management computer. The infrared probe determines temperature at the position remote from the aircraft and generates a remote temperature signal received by the performance management computer. The temperature probe determines temperature at the aircraft and generates a local temperature signal received by the performance management computer. The weather radar determines wind at the position remote from the aircraft and generates a remote wind signal received by the performance management computer. The inertial navigation system determines wind at the aircraft and generates a local wind signal received by the performance management computer.