US and Argentine authorities were investigating how a stick of dynamite in a college student's checked luggage ended up on a Houston-bound flight.
There was no indication terrorism was involved in any of the incidents, which caused two flights to be diverted, others to be delayed and passengers to be questioned.
The dynamite was discovered during a baggage search in an inspection station at Bush Intercontinental Airport shortly after Continental Airlines Flight 52 from Argentina landed early on Friday.
Argentina's chief of airport security police, Marcelo Sain, said in a TV interview on Friday that authorities there were in contact with US officials as they opened their own probe into how the explosive got into the baggage.
The student, 21-year-old Howard McFarland Fish, was charged with carrying an explosive aboard an aircraft and was in the custody of US Immigration and Customs Enforcement.
Houston Fire Department Assistant Chief Omero Longoria said Fish told authorities he works in mining and often handles explosives.
Fish's father, Howard, said he is certain his son, who bought the dynamite while visiting a silver mine while traveling in South America, intended no harm.
"It's a 21-year-old kid not paying careful attention to the press and thinking it would be cool to have a piece of dynamite," Howard Fish, of Old Lyme, Connecticut, said on Friday night.
The US Attorney's Office in Houston said he would appear before a federal magistrate tomorrow. Carrying an explosive aboard an aircraft carries a maximum penalty of 10 years in prison and a fine of up to US$250,000.
The incident could have been disastrous and raises questions about security in overseas airports, said Bill Waldock, aviation safety professor at Embry-Riddle Aeronautical University in Arizona, adding that dynamite can be unstable if it is old.
"You're in a pressurized airplane, you get a detonation in the cargo hold, it could blow a hole in the airplane big enough to bring it down," he said.