Maximum altitude on an instrument approach chart is the altitude at or below which aircraft are required to maintain altitude.

• A. The altitude you must reach before descending prior to the runway
• B. The altitude to reach before the runway
• C. The altitude at or below which aircraft are required to maintain altitude
• D. The altitude of the airport elevation

Answer: (C)

On an instrument approach chart, vertical constraints tell you how you must manage your altitude as you fly the procedure. The maximum altitude is the altitude value you may not exceed on that segment; you are required to be at or below it and to maintain that altitude there until you are cleared to descend further. This wording—“the altitude at or below which aircraft are required to maintain altitude”—fits exactly, because it specifies a ceiling you must hold rather than a point to reach or a general elevation.

The other options describe different ideas: one speaks to a level to reach before starting descent, another is vague about reaching a point before the runway, and the last is simply the airport’s elevation, which isn’t a segment-wide altitude restriction on the approach.