A method of real-time analyzing, with a flight management systems of an aircraft, a takeoff sequence of the aircraft on a predetermined runway, the method comprising: receiving at the FMS, real-time aircraft variables associated with the aircraft and real-time condition variables associated with an environment in which the aircraft is located; receiving at the FMS, from sensors (54, 58) on the aircraft, real-time data of an actual velocity of the aircraft and a real-time acceleration (a) of the aircraft; estimating, using the FMS, a final estimated velocity based on the actual velocity and the real-time acceleration (a), wherein the final estimated velocity comprises an estimation of a velocity that will occur in the future of the takeoff sequence; the method characterised by: calculating, using the FMS, the takeoff reference velocity, using at least one of the real-time aircraft variables and the real-time condition variables, wherein the takeoff reference velocity represents what a value of the actual velocity of the aircraft should be, at a given time, based on the received real-time aircraft variables and real-time condition variables; comparing, using the FMS, the final estimated velocity to the takeoff reference velocity to determine if the final estimated velocity is within a predetermined range of the takeoff reference velocity; and altering, using the FMS, at least one of a thrust, adjusting a flap mounted to the aircraft, or adjusting a slat mounted to the aircraft when the comparing indicates the final estimated velocity is not within the predetermined range. receiving at the FMS, real-time aircraft variables associated with the aircraft and real-time condition variables associated with an environment in which the aircraft is located; receiving at the FMS, from sensors (54, 58) on the aircraft, real-time data of an actual velocity of the aircraft and a real-time acceleration (a) of the aircraft; estimating, using the FMS, a final estimated velocity based on the actual velocity and the real-time acceleration (a), wherein the final estimated velocity comprises an estimation of a velocity that will occur in the future of the takeoff sequence; the method characterised by: calculating, using the FMS, the takeoff reference velocity, using at least one of the real-time aircraft variables and the real-time condition variables, wherein the takeoff reference velocity represents what a value of the actual velocity of the aircraft should be, at a given time, based on the received real-time aircraft variables and real-time condition variables; comparing, using the FMS, the final estimated velocity to the takeoff reference velocity to determine if the final estimated velocity is within a predetermined range of the takeoff reference velocity; and altering, using the FMS, at least one of a thrust, adjusting a flap mounted to the aircraft, or adjusting a slat mounted to the aircraft when the comparing indicates the final estimated velocity is not within the predetermined range. calculating, using the FMS, the takeoff reference velocity, using at least one of the real-time aircraft variables and the real-time condition variables, wherein the takeoff reference velocity represents what a value of the actual velocity of the aircraft should be, at a given time, based on the received real-time aircraft variables and real-time condition variables; comparing, using the FMS, the final estimated velocity to the takeoff reference velocity to determine if the final estimated velocity is within a predetermined range of the takeoff reference velocity; and altering, using the FMS, at least one of a thrust, adjusting a flap mounted to the aircraft, or adjusting a slat mounted to the aircraft when the comparing indicates the final estimated velocity is not within the predetermined range.