A jury convicted a former British Airways computer specialist on Monday of plotting with U.S.-born extremist cleric Anwar al-Awlaki to blow up an airplane in an attack intended to kill hundreds of people.

Rajib Karim, a 31-year-old Bangladeshi man, was convicted of four counts of engaging in preparation for terrorist attacks. He had already pleaded guilty to five other terrorism offenses, but denied plotting an attack in Britain.

A jury deliberated for 16 hours before agreeing with prosecutors who said Karim used his position at the airline to conspire with al-Awlaki, a notorious radical preacher associated with al-Qaida and thought to be hiding in Yemen. At one point, encouraged by al-Awlaki, he applied for training as a flight attendant.

Colin Gibbs, a counterterrorism lawyer for the Crown Prosecution Service, said Karim "was plotting with the cleric to use his job at BA to kill hundreds of innocent people."

"The most chilling element of this case is probably the fact that Karim tried to enroll as cabin crew and anyone can imagine how horrific the consequences of this could have been, had he succeeded," Gibbs said.

Prosecutor Jonathan Laidlaw told the court that Karim "sought work in this country of the sort which would be useful to him or a terrorist organization in planning an attack _ an attack of the sort which might result in the wholesale loss of life."

Prosecutors said that in heavily encrypted exchanges, Al-Awlaki quizzed Karim about details of security flaws and urged the aspiring terrorist to train as a flight attendant to assist plans to use suicide bombers or mail bombs to down U.S.-bound flights.

"Our highest priority is in the U.S.," al-Awlaki told Karim in an encrypted message, thought by police to have been sent in February 2010. "The question is, with the people you have, is it possible to get a package, or a person with a package, onboard a flight heading to the U.S?"

The cleric told Karim he hoped he would be able to supply "critical and urgent information" related to airline security because of his role at BA. He told the airline worker he "may be able to play a crucial role," in future attacks.

Karim, who was arrested at his BA desk in the northern English city of Newcastle in February 2010, was convicted after a trial at Woolwich Crown Court in London. He is due to be sentenced on March 18.

Karim, who studied electronic engineering at a university in Manchester between 1998 and 2002 and has a British wife, returned to Britain in 2006 and joined BA the following year.

He admitted helping make a video about an organization called Jamaat-Ul Mujahideen Bangladesh because he believed it had been misrepresented as a terrorist organization.

He pleaded guilty to helping produce a terrorist group's video, fundraising and volunteering for terror abroad _ but insisted he never planned an attack in Britain.

But Laidlaw said that Karim became disillusioned with Jamaat-Ul Mujahideen's reluctance to carry out attacks overseas, and applied for jobs in Britain with BA and with Balfour Beatty, a construction company involved in major infrastructure projects.

The prosecutor said that Karim spent several years at BA cultivating a low profile, presenting himself as "mild-mannered, well-educated and respectful."

All the while he was trading messages with al-Awlaki _ some through Karim's brother, who had traveled from Bangladesh to Yemen.

In one exchange, Karim expressed concern that al-Awlaki had been killed in a U.S. drone strike. It prompted the cleric to send a 30-second audio file, offering proof he was still alive.

The messages showed that Al-Awlaki probed Karim for details on how someone on a terrorist watch list, or from a country likely to be under close scrutiny by Western intelligence services might evade security measures.

He also urged Karim to exploit a strike by BA cabin crew, during which managers asked other staff to train for cabin duties. Though Karim put himself forward, he was rejected because he had not served a required five years with the airline.

Al-Awlaki is thought to have orchestrated the unsuccessful October plot to send mail bombs on planes from Yemen to the U.S., hidden in the toner cartridges of computer printers. He is also believed to have inspired or helped coordinate the failed December 2009 bombing of a Detroit-bound airliner and the 2009 shooting at a U.S. Army base in Fort Hood, Texas.

Last year, Britain's top law enforcement official cited Karim's case as proof that al-Qaida's offshoot in Yemen, al-Qaida in the Arabian Peninsula, was attempting attacks on U.K. and U.S.

Home Secretary Theresa May told an audience of intelligence chief and security experts that the group had "shown the ability to project a threat far beyond the borders of Yemen."