Flights may be delayed today due to a variety of reasons, including poor weather, air traffic control delays, maintenance issues, late arrival of incoming aircraft, or crew availability. Poor visibility, high winds, or other unsafe weather conditions can lead to ground delays. Air traffic control delays are caused by limited airspace or capacity available for flight operations at a given time. Maintenance issues may also lead to delays, as aircraft must be evaluated and repaired as necessary. Delays may also occur from late incoming flights, as they must arrive, depart, and be replaced with a different aircraft. Lastly, delays may occur due to crew availability, including crew rest and operating time limitations.