<p>The US Federal Aviation Administration's (FAA) system that alerts pilots and other flight personnel about hazards or any changes to airport facility services and relevant procedures was not processing updated information, the civil aviation regulator's website showed on Wednesday.</p>.<p>In an advisory, the FAA said its NOTAM (Notice to Air Missions) system had "failed". There was no immediate estimate for when it would be back, the website showed, though NOTAMs issued before the outage were still viewable.</p>.<p>Over 400 flights were delayed within, into, or out of the United States as of Wednesday 5.31 am ET, flight tracking website <em>FlightAware </em>showed. It was not immediately clear if the outage was a factor.</p>.<p>"Technicians are currently working to restore the system," the website showed. The FAA was not immediately available for further comment.</p>.<p>A NOTAM is a notice containing information essential to personnel concerned with flight operations, but not known far enough in advance to be publicized by other means.</p>.<p>Information can go up to 200 pages for long-haul international flights and may include items such as runway closures, general bird hazard warnings, or low-altitude construction obstacles. </p>
<p>The US Federal Aviation Administration's (FAA) system that alerts pilots and other flight personnel about hazards or any changes to airport facility services and relevant procedures was not processing updated information, the civil aviation regulator's website showed on Wednesday.</p>.<p>In an advisory, the FAA said its NOTAM (Notice to Air Missions) system had "failed". There was no immediate estimate for when it would be back, the website showed, though NOTAMs issued before the outage were still viewable.</p>.<p>Over 400 flights were delayed within, into, or out of the United States as of Wednesday 5.31 am ET, flight tracking website <em>FlightAware </em>showed. It was not immediately clear if the outage was a factor.</p>.<p>"Technicians are currently working to restore the system," the website showed. The FAA was not immediately available for further comment.</p>.<p>A NOTAM is a notice containing information essential to personnel concerned with flight operations, but not known far enough in advance to be publicized by other means.</p>.<p>Information can go up to 200 pages for long-haul international flights and may include items such as runway closures, general bird hazard warnings, or low-altitude construction obstacles. </p>