A computer-implemented method for calculating vertical trajectory values, the method comprising: obtaining aircraft performance data for a particular aircraft and atmospheric condition data associated with an air route; calculating a cost-efficient vertical trajectory for the air route, based on the aircraft performance data and the atmospheric condition data, wherein the cost-efficient vertical trajectory comprises a plurality of altitude values for minimizing cost for the particular aircraft during travel of the air route; obtaining an altitude consistency threshold comprising a time period for which the particular aircraft is configured to remain at a particular altitude; and adjusting the cost-efficient vertical trajectory using the altitude consistency threshold, to create an optimized vertical trajectory for the aircraft route, by: when one or more of the plurality of altitude values do not comply with the altitude consistency threshold, shifting the one or more of the plurality of altitude values to comply with the altitude consistency threshold; and when the plurality of altitude values do comply with the altitude consistency threshold, identifying transitions between each of the plurality of altitude values; removing a first subset of the transitions comprising climb closely followed by descent; and removing a second subset of the transitions comprising descent closely followed by climb. obtaining aircraft performance data for a particular aircraft and atmospheric condition data associated with an air route; calculating a cost-efficient vertical trajectory for the air route, based on the aircraft performance data and the atmospheric condition data, wherein the cost-efficient vertical trajectory comprises a plurality of altitude values for minimizing cost for the particular aircraft during travel of the air route; obtaining an altitude consistency threshold comprising a time period for which the particular aircraft is configured to remain at a particular altitude; and adjusting the cost-efficient vertical trajectory using the altitude consistency threshold, to create an optimized vertical trajectory for the aircraft route, by: when one or more of the plurality of altitude values do not comply with the altitude consistency threshold, shifting the one or more of the plurality of altitude values to comply with the altitude consistency threshold; and when the plurality of altitude values do comply with the altitude consistency threshold, identifying transitions between each of the plurality of altitude values; removing a first subset of the transitions comprising climb closely followed by descent; and removing a second subset of the transitions comprising descent closely followed by climb. when one or more of the plurality of altitude values do not comply with the altitude consistency threshold, shifting the one or more of the plurality of altitude values to comply with the altitude consistency threshold; and when the plurality of altitude values do comply with the altitude consistency threshold, identifying transitions between each of the plurality of altitude values; removing a first subset of the transitions comprising climb closely followed by descent; and removing a second subset of the transitions comprising descent closely followed by climb. identifying transitions between each of the plurality of altitude values; removing a first subset of the transitions comprising climb closely followed by descent; and removing a second subset of the transitions comprising descent closely followed by climb.