1.VerbTo periodically climb to higher and higher altitudes during cruise flight, as the aircraft becomes lighter from fuel burnoff, to take advantage of the reduced drag at higher altitudes; like cruise-climbing, but with the aircraft climbing in discrete steps instead of continuously.
"The flight plan called for step climbing from an initial cruising altitude of FL330 to the final altitude of FL350 halfway through the flight."
2.NounAn instance of step climbing.
"The step climb from FL340 through FL360 and FL380 to FL400 will reduce our fuel burn compared to if we cruised at FL340 for the whole flight."