On the Flightradar24 airport schedule boards and flight history pages, a grey dot or icon indicates that a flight is scheduled, but no additional real-time status or tracking information is currently available. This is common for flights that are still several hours or days away from departure, where the airline hasn't yet provided a "Live" update or the aircraft hasn't yet been assigned a transponder signal that the network can pick up. It essentially acts as a "placeholder" in the system. Once the flight begins its ground operations or takes off, the icon typically changes color: green for on-time, orange for a slight delay, or red for a significant delay or cancellation. If you see a grey icon for an active flight, it might also mean the aircraft is flying in an area with limited coverage (like deep oceanic regions) or is using a "blocked" transponder for privacy reasons, though a black dotted line on the map specifically indicates an estimated position outside of coverage.