One advantage of plan filing is that the plane's proposed location is recorded. Having a flight plan on file prior to taking off insures that if the plane does not reach its intended destination, the search teams deployed will know where to look. Plan filing alerts air traffic controllers patrolling the air space along your route. Air traffic controllers can alert pilots to potentially hazardous weather and traffic issues when controllers can anticipate the plane's location. This helps to prevent in-flight accidents. Filing a plan also insures that the plane is not passing through any restricted air spaces.
A disadvantage of filing a plan is that the plane is locked in to a predetermined flight path. Once the plan is filed, it is difficult to amend the plan immediately before or during flight unless an emergency situation arises or weather conditions require the plane to change course. Flights that have a filed plan are required to stay as close to their predetermined course as possible. In the event that the plane must change courses, the pilot is required to notify the nearest air traffic controller prior to making any in-flight changes to the filed plan.
Another advantage of plan filing is that in the event the flight does not reach its intended destination, there is a predetermined travel route that authorities can use as a guide to search for the downed plane. Plan filing also highlights airports located along or near the plane's route, which can be valuable information in case of an in-flight emergency. When a pilot fails to close out a flight plan upon reaching his destination, local officials will begin to initiate a search for the plane, beginning with the runways of the destination airport. Sending out a search and rescue team is a last resort to search for a missing plane.
A final advantage of plan filing is that the pilot will know the route prior to the flight and can check for weather conditions before taking off. This allows the pilot to anticipate weather and any problems that might arise due to inclement weather situations while in flight. The pilot can also contact local weather services via radio while in flight to become apprised of any weather changes or sudden developments that may impede flight travel.
