The altitude corresponding to any of the “AirFlightActions” indicates the Flight’s altitude as it begins that action. For instance, if the Flight is Transiting from its Anchor to its Orbit, then the altitude shown for the Transit action would actually be the Anchor’s altitude which the Flight is leaving as it climbs/descends while Transiting to the Orbit.

Ditto for fuel consumption, by the way. The Flight’s fuel consumption on any leg is based upon its altitude (and speed) as it begins the action. This makes sense: If the Flight is climbing from a low to a high altitude, its fuel burn rate is higher (based on the low altitude), which corresponds with its higher power setting for the climb. Conversely, if a Flight descending from a high to a low altitude, its fuel burn rate is lower (based on the high altitude), corresponding to its lower power setting for the descent.