Colorado ? The Federal Aviation Administration has opened its own investigation into the 50-mile flight of the helium balloon that briefly delayed flights at Denver International Airport after a couple reported that their 6-year-old son may have been on board, an official said Tuesday.

FAA spokesman Mike Fergus said the agency investigates civil allegations rather than criminal ones. He declined to provide details on the nature of the FAA probe or its possible outcome.

Larimer County Sheriff Jim Alderden has said investigators believe amateur storm chasers Richard and Mayumi Heene called 911 Thursday saying they thought their son, Falcon, was aboard the large helium balloon that floated away from their yard in Fort Collins in a bid to get publicity for a reality TV show.

The balloon landed 50 miles away near Denver International Airport. Some flights had to be changed to a different runway for 20 minutes. Falcon was found safe at home.

Alderden said he is seeking charges against the Heenes including conspiracy, contributing to the delinquency of a minor, making a false report to authorities, and attempting to influence a public servant. The most serious charges are felonies and carry a maximum sentence of six years in prison.