An airflow arresting apparatus is provided configured to reside above an electronics rack within a data center. The apparatus includes an airflow arrester and a track mechanism. The airflow arrester includes a collapsible panel sized and configured to reside above the electronics rack, and when operatively positioned above the electronics rack, to extend vertically above the electronics rack and at least partially block airflow from passing over the electronics rack between the air outlet and air inlet sides of the rack. The track mechanism is sized and configured to reside above the electronics rack, and the airflow arrester is slidably engaged with the track mechanism. Positioning of the airflow arrester at a desired location above the electronics rack is facilitated by the airflow arrester slidably engaging the track mechanism.