Systems and methods for ACM trajectory include receiving data at a communications receiver; decoding the received data based on a selected MODCOD; monitoring a number of iterations used to decode the data using the selected MODCOD; comparing the number of iterations used to decode the data using the first selected MODCOD to a reference number of iterations; and adjusting a SNR threshold value for the selected MODCOD where the number of iterations used to decode the data using the first selected MODCOD is greater than the reference number of iterations.