When you land at an airport in Instrument Flight Rules (IFR) conditions, the method for closing your flight plan depends on whether the airport has an active control tower. If the destination is a controlled airport, the control tower will automatically close your IFR flight plan for you upon landing; no further action is required from the pilot. However, if the airport is uncontrolled (or the tower is closed for the night), the pilot is solely responsible for closing the flight plan to prevent a Search and Rescue (SAR) mission from being triggered. In IFR conditions at an uncontrolled field, the pilot usually closes the flight plan with Air Traffic Control (ATC) over the radio while still in the air, but only once they have the runway in sight and can safely complete the landing. If they wait until after landing, they must contact a Flight Service Station (FSS) or ATC via a dedicated telephone number or through a digital app. Failing to close the flight plan within 30 minutes of your estimated arrival will cause authorities to initiate an emergency search.