To ensure compliance with navigation, what must be factored regarding cruising altitudes?

Considering compliance with navigation and the appropriate use of cruising altitudes, it is crucial to factor in magnetic track cruising altitudes. This is important because cruising altitudes are often dictated by the direction of flight and the magnetic variation in the area. In general, aircraft operating at altitudes above 3,000 feet AGL (Above Ground Level) maintain specific altitudes based on their magnetic track: odd altitudes for magnetic tracks from 0 to 179 degrees and even altitudes for magnetic tracks from 180 to 359 degrees. This convention helps to maintain safe vertical separation between aircraft flying in opposite directions.

The other considerations in this question, while important in different contexts, do not directly influence the compliance with the navigation altitudes in the same way. For example, different types of airports might affect approach and departure procedures, but they are not intrinsic to the determination of cruising altitudes. Weather conditions are indeed critical for safety and operational efficiency but do not govern how altitudes are assigned or maintained for navigation purposes. Lastly, flight plan approval enables transit through various airspace but does not define the cruising altitudes themselves as related to magnetic tracks.