Abdulla Ahmed Ali, 28, Tanvir Hussain, 28, and Assad Sarwar, 29, were convicted on Monday of conspiring to detonate bombs hidden in soft drink bottles in mid-flight suicide attacks.
The bombers intended to simultaneously destroy at least seven planes carrying over 200 passengers each between London's Heathrow airport and the United States and Canada in August 2006, prosecutors said.
The suspected al-Qaeda plot led to a tight of security restrictions worldwide on the amount of liquids passengers could take on board aircraft.
Four other men were found not guilty of the plot and the jury failed to reach a verdict in the case of an eighth suspect.
The conspirators were caught just days from putting the plan into operation following the largest surveillance operation of its kind being carried out by British police.