Up to five years in federal prison and up to a $250,000 fine is the punishment range for making a terroristic threat directed at an in-flight aircraft.
On Monday night, a Southwest Airlines jetliner bound for San Antonio from Baltimore was directed to a remote area at San Antonio International Airport upon landing.
A threat had been received concerning the flight, according to airport spokesman Rich Johnson.
The aircraft was searched after all passengers had been transferred by bus to the terminal.
No explosives or dangerous material was found.
The Federal Bureau of Investigation has launched an investigation.