Rajib Karim, a 31-year-old Bangladeshi man, was convicted last month of four counts of engaging in preparation for terrorist attacks. He already had pleaded guilty to five other terrorism offenses, but denied plotting an attack in Britain.
Justice Calvert-Smith called Karim's offenses "of the utmost gravity" in Friday's sentencing at Woolwich Crown Court.
Prosecutors said Karim used his position at the airline to conspire with al-Awlaki, a notorious US-born radical preacher associated with al-Qaida and thought to be hiding in Yemen.
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