What does the black arrow mark on an airport diagram indicate?

The black arrow mark on an airport diagram indicates the highest obstacle on an Instrument Approach Procedure (IAP), Standard Instrument Departure (SID), or Standard Terminal Arrival Route (STAR). This marking is crucial for pilots as it provides vital safety information regarding potential obstructions that could impact flight operations during critical phases of flight such as approach and departure.

Understanding the height and location of these obstacles is essential for flight safety, as it ensures that pilots can maintain appropriate altitudes during their approach or departure, avoiding any collisions with structures or terrain. The clarity of this marking helps pilots make informed decisions when navigating near airports, especially in varied terrain or densely built environments.