A schedule management system for managing air traffic comprising multiple aircraft that are within a defined airspace and approaching an arrival airport, each of the multiple aircraft having existing trajectory parameters comprising three-dimensional position and velocity, the schedule management system comprising: on-aircraft flight management systems individually associated with the multiple aircraft and adapted to determine aircraft trajectory and flight-specific cost data of the aircraft associated therewith, the flight-specific cost data comprising the cost of fuel and other direct and time related costs; an air traffic control system adapted to monitor the multiple aircraft but is not located on any of the multiple aircraft, the air traffic control system having a decision support tool, the air traffic control system being operable to acquire the aircraft trajectory and the flight-specific cost data from the flight management systems and generate a scheduled time-of-arrival for each of the multiple aircraft for at least one location along an approach to the arrival airport; wherein if any of the multiple aircraft miss the STA thereof at the at least one location and thereby delays a second of the multiple aircraft flying towards the at least one location to impose a later STA for the second aircraft, the air traffic control system is operable to: transmit the aircraft trajectory and the flight-specific cost data to the decision support tool; utilize the decision support tool to compute a plurality of possible alternative trajectories which would adequately delay the second aircraft to meet the imposed later STA for the second aircraft while also conserving flight-specific costs by potentially initiating an early descent; provide the plurality of possible alternative trajectories to a human user via a user interface; and transmit, to the second aircraft, instructions to follow one of the plurality of possible alternative trajectories selected by the human user. on-aircraft flight management systems individually associated with the multiple aircraft and adapted to determine aircraft trajectory and flight-specific cost data of the aircraft associated therewith, the flight-specific cost data comprising the cost of fuel and other direct and time related costs; an air traffic control system adapted to monitor the multiple aircraft but is not located on any of the multiple aircraft, the air traffic control system having a decision support tool, the air traffic control system being operable to acquire the aircraft trajectory and the flight-specific cost data from the flight management systems and generate a scheduled time-of-arrival for each of the multiple aircraft for at least one location along an approach to the arrival airport; wherein if any of the multiple aircraft miss the STA thereof at the at least one location and thereby delays a second of the multiple aircraft flying towards the at least one location to impose a later STA for the second aircraft, the air traffic control system is operable to: transmit the aircraft trajectory and the flight-specific cost data to the decision support tool; utilize the decision support tool to compute a plurality of possible alternative trajectories which would adequately delay the second aircraft to meet the imposed later STA for the second aircraft while also conserving flight-specific costs by potentially initiating an early descent; provide the plurality of possible alternative trajectories to a human user via a user interface; and transmit, to the second aircraft, instructions to follow one of the plurality of possible alternative trajectories selected by the human user. transmit the aircraft trajectory and the flight-specific cost data to the decision support tool; utilize the decision support tool to compute a plurality of possible alternative trajectories which would adequately delay the second aircraft to meet the imposed later STA for the second aircraft while also conserving flight-specific costs by potentially initiating an early descent; provide the plurality of possible alternative trajectories to a human user via a user interface; and transmit, to the second aircraft, instructions to follow one of the plurality of possible alternative trajectories selected by the human user.