The same Detroit-bound Northwest Airlines flight that was attacked on Christmas Day saw another security scare Sunday after a confrontation with a sick passenger, officials said.
Security and airline personnel have been on edge since authorities charged a passenger from Nigeria with attempting to detonate a hidden explosive device while his flight from Amsterdam approached Detroit on Friday.
In the Sunday incident, the flight crew became concerned after the man -- also Nigerian -- became sick and spent about an hour locked in the bathroom, officials said.
"This raised concerns, so an alert was raised," FBI spokeswoman Sandra Berchtold said. "The investigation shows that this was a nonserious incident and all is clear at this point."
After the flight crew became concerned, the pilot of the Sunday flight had requested emergency assistance upon arrival, sending federal authorities scrambling to respond to a potential danger.
The Transportation Security Administration said the airline alerted authorities to a "disruptive passenger" on board Flight 253, who was taken into custody when the plane landed.
Two law enforcement officials, speaking on condition of anonymity because they were not authorized to discuss the incident, said the crew apparently acted out of an abundance of caution in alerting authorities.
Post-flight interviews by investigators determined the passenger was a legitimate businessman who posed no security threat to the plane, the two law enforcement officials said.
White House officials briefed President Obama on the incident, which generated multiple law-enforcement reports of a disruptive passenger aboard a Detroit-bound plane.
An apparent malfunction in a device designed to detonate the high explosive PETN may have been all that saved the 278 passengers and the crew aboard Northwest Flight 253 on Christmas Day. No undercover air marshal was on board, and passengers subdued the suspect, Umar Farouk Abdulmutallab, 23, of Nigeria.
Mr. Abdulmutallab was hospitalized with burns from the attack and was read an indictment filed Saturday in federal court in Detroit charging him with attempting to destroy or wreck an aircraft and placing a destructive device in a plane. He was released from the hospital Sunday to the custody of federal marshals, who would not reveal where he was being held.
Mr. Abdulmutallab was on a watch list, but not one that denied him passage by air into the United States. His own father had discussed concerns about his radical religious views before the attack.
Still, in appearances on Sunday talk shows, Homeland Security Secretary Janet Napolitano said the traveling public "is very, very safe."
"This was one individual literally of thousands that fly and thousands of flights every year," Ms. Napolitano said, "and he was stopped before any damage could be done. I think the important thing to recognize here is that once this incident occurred, everything happened that should have."
Even so, airport security and intelligence played no role in thwarting the plot. Mr. Abdulmutallab was carrying PETN, also known as pentaerythritol, the same material convicted shoe bomber Richard Reid used when he tried to destroy a trans-Atlantic flight in 2001 with explosives hidden in his shoes. Mr. Abdulmutallab is alleged to have carried the explosive in condomlike pouches attached to his body.
Mr. Abdulmutallab was on a "generic" terrorist watch list, which includes more than half a million names, but was not elevated to a no-fly list or even designated for additional security searches, Ms. Napolitano said. That would have required "specific, credible, derogatory information," she said.
"We did not have the kind of information that under the current rules would elevate him," she said.
Ms. Napolitano said the Obama administration is considering changing those rules.
Despite being on the broad terrorist watch list, Mr. Abdulmutallab, who comes from a prominent and wealthy Nigerian family, had a multiple-entry U.S. visa that was issued last year. U.S. officials say he came to the attention of American intelligence in November when his father expressed concerns to the U.S. Embassy in Nigeria about his son's extremist views.
Ms. Napolitano said Mr. Abdulmutallab was screened properly before getting on the flight to Detroit in Amsterdam.
The administration is also investigating aviation detection systems to see how the alleged attacker managed to get on board the Northwest flight in Amsterdam with explosive materials, White House spokesman Robert Gibbs said.
No other flights were known to have been targeted. However, Mr. Gibbs said, federal authorities took precautionary steps "to assume and plan for the very worst." Ms. Napolitano said there is no indication yet Mr. Abdulmutallab is part of a larger terrorist plot, although his possible ties to al Qaeda are still under investigation.
The United States is reviewing what security measures were used in Amsterdam where he boarded the flight.
"Now the forensics are being analyzed with what could have been done," Ms. Napolitano said.
Additional security measures are in place at airports around the world that are likely to slow travelers. Ms. Napolitano advised getting to airports earlier.
Congress is preparing to hold hearings on what happened and whether rules need to be changed.
"It's amazing to me that an individual like this who was sending out so many signals could end up getting on a plane going to the U.S.," said Senate Minority Leader Mitch McConnell, Kentucky Republican.
Mr. Gibbs appeared on ABC's "This Week," NBC's "Meet the Press" and CBS' "Face the Nation." Ms. Napolitano spoke on CNN's "State of the Union" as well as on NBC and ABC. Mr. McConnell appeared on ABC.
Pamela Hess reported from New York. Associated Press writers Ed White in Detroit and Devlin Barrett in Washington contributed to this report.