(WVLT/AP) -- The Federal Aviation Administration cleared all airline traffic within 250 miles of Memphis this afternoon, grounding an unknown number of flights around the country.
It was blamed on the failure of communications equipment at the regional air-traffic control center in the Bluff City.
Air traffic control centers in adjacent regions handled flights that were already in the air when the problem was discovered.
High-altitude flights through the region were discontinued in Alabama, Mississippi, Arkansas, Missouri, Indiana, Kentucky and Tennessee.
After about two hours, the FAA started allowing departing and arriving flights to resume at airports inside the 250-mile radius.
Flights from other U.S. airports were still being re-routed around the Memphis region.
The FAA action applied to all large, high-altitude planes, whether they were carrying passengers or cargo.
Memphis, with the headquarters of shipping giant FedEx, is the world's busiest airport for cargo. The Memphis airport is also a hub for Northwest Airlines.
For details on any delayed or canceled flights out of McGhee Tyson Airport in Knoxville, click the link below.