The bomb found on the cargo plane at East Midlands Airport last month was timed to detonate over the eastern seaboard of the United States, Scotland Yard has said.
The device, which was removed from a UPS aircraft by Leicestershire police officers shortly after 3.30am on October 29, was timed to go off some seven hours later, police said.
A Scotland Yard spokesman said: "If the device had not been removed from the aircraft the activation could have occurred over the eastern seaboard of the US."
The bomb, disguised as an ink cartridge, was found following a tip-off from Saudi intelligence.
A Scotland Yard spokesman said the cargo plane arrived at East Midlands Airport from Cologne at 2.13am BST and left at 4.20am BST "after the suspect package had been removed".
"Forensic examination has indicated that if the device had activated it would have been at 10.30am BST," he said.
"If the device had not been removed from the aircraft the activation could have occurred over the eastern seaboard of the US."
He added that the bomb was "disrupted" when explosive officers removed the printer cartridge from the printer during their initial examination of the device at about 7.40am BST.
Experts in Germany said the bomb, and another found in Dubai, contained at least 300g (10.58oz) of the powerful explosive PETN.
It had travelled through a UPS hub at Germany's Cologne airport before being detected in the UK following the tip-off, officials said.
