A series of red flashes directed at an aircraft in flight communicates what?

When a series of red flashes is directed at an aircraft in flight, it indicates that the airport is unsafe for landing. This signal serves as a warning to the pilot, advising them that conditions at the airport do not allow for a safe landing, either due to an emergency on the runway, closed facilities, or other hazardous situations.

In the context of air regulations and communication, it is crucial for pilots to understand and respond appropriately to visual signals. Recognizing these signals ensures safety and effective decision-making during critical phases of flight.