Simplify the following text for a Grade 13 native English-speaking person.
Original: The Federal Aviation Administration ( FAA ) is an agency of the United States Department of Transportation with authority to regulate and oversee all aspects of civil aviation in the U.S. .
Simplified: The Federal Aviation Administration ( FAA ) is an agency of the United States Department of Transportation with authority to regulate and oversee all aspects of civil aviation in the U.S. ( National Airworthiness Authority ) .