The present disclosure generally relates to systems and methods for determining a four-dimensional (4D) trajectory of an aircraft without requiring aircraft performance data or meteorological data. The techniques can include: detecting a plurality of 4D aircraft states of the aircraft, determining, for each of a plurality of pairs of adjacent aircraft states, a respective aircraft transition, detecting a plurality of pairs of repeat adjacent aircraft transition, discarding, for each pair of repeat adjacent aircraft transitions, a respective aircraft state from the plurality of aircraft states, and electronically transmitting the plurality of aircraft states after the discarding.