So, I have a set of flight tracks, all uniquely identified, and I'm trying to separate the flights into phases. I've had great success for the takeoff and landing portions, as well as the cruising portion, but the ascent and descent is giving me a hard time.

When a plane is ascending or descending, it gets a "C" or "D" in the altitude change column. I thought that I'd be able to characterize the ascent to cruising or descent to landing phase merely by the presence of C or D (when it levels off, it gets a "-".)

Sometimes during an ascent to cruising or descent to landing, however, the plane will briefly get a "-" or worse an opposite letter, which kills the consistency in characterizing the phases of the flight. But, if a "-" or the opposite letter is present, it will always be preceded or followed by the correct flight status.

So, is there a way to change an attribute's value according to that flight_id (a separate value) and the value preceding or following it?