The detained cargo plane belonging to the United Arab Emirates Air Force, which was found laden with arms and ammunition, took off for China's Xianyang city on Thursday after being grounded in Kolkata for four days.
The China-bound plane was detained on September 6 for not declaring the consignment it was carrying.
Airport sources confirmed that the airplane carrying 10 crew members, including the pilot, took off at 9.30 am.
A defence spokesman in Kolkata said the plane's clearance was received from the Air Headquarters late on Wednesday night.
The external affairs ministry had given the green signal to the ministry of defence and customs authorities that the C-130 Hercules plane could be allowed to leave the NSC Bose International Airport.
The aircraft was grounded here since Sunday evening and its crew members interrogated.
The Indian government gave the clearance after it was told by UAE authorities that the plane's pilot had committed a "technical error" over declaring the on-board arms and ammunition for which they expressed regret.
The external affairs ministry had said in a statement that the matter would be resolved in the spirit of the close and friendly ties between India and the UAE.
The statement said the UAE authorities both in New Delhi and Abu Dhabi have since formally regretted the omission in clearly indicating items carried by the aircraft and have described it as a "technical error".The plane, which had started from Abu Dhabi, had made a scheduled transit halt in Kolkata for refueling on Sunday when the consignment was detected.