Last month, government prosecutors failed to convict three other men of helping to plan the deadly London transit bombings of 2005 - the worst attack on Britain's capital since World War II.
In Monday's decision, Abdulla Ahmed Ali and co-conspirators Assad Sarwar and Tanvir Hussain were convicted of trying to make a bomb out of hydrogen peroxide.
But the jury struggled to find enough evidence to support prosecutors' claims that the men planned suicide attacks targeting passenger jets flying from London to major North American cities.
The three will be sentenced at a later date.
The men were arrested on Aug. 10, 2006 - a date that would go down in history as the day when air travel changed dramatically.
Airports in the United States and Europe ground to a halt with hundreds of flights canceled over security concerns. Planes were stuck on runways for hours. Tempers flared as passengers lined up to surrender carry-on items under new security precautions that severely restricted the quantity of liquids in their luggage - limits that remain in place until today.
Prosecutors said they would consider a request for retrial of the three men. The jury failed to reach verdicts Monday on four other men facing the same charges - Ibrahim Savant, Arafat Waheed Khan, Waheed Zaman and Umar Islam. Prosecutors would consider a retrial for them as well.
An eighth man, Mohammed Gulzar, was found not guilty.
Prosecutor Peter Wright said during the trial that the men planned to attack United Airlines, American Airlines and Air Canada flights at the height of the 2006 summer vacation season.
British and US intelligence officers said the alleged plot was uncovered during a marathon investigation that led to a number of different sites including a bomb factory in eastern London, British woodlands where chemicals had been dumped, Japan, Mauritius, South Africa and Pakistan's lawless tribal areas where conversations were intercepted.
Police swooped down and arrested two dozen suspects in dawn raids across Britain on Aug. 10, 2006.
A lawyer for Ali, a 27-year-old computer-systems engineering graduate and the alleged ringleader of the group, insisted last month he was guilty only of planning a childish stunt to make a political point.
Ali told the court they planned to set off a small bomb at a site such as the Houses of Parliament or Heathrow Airport to advertise a propaganda documentary protesting the West's actions in Afghanistan and Iraq. He denied intending to kill anyone.
"It was childish, it was stupid, but it is not murder," the lawyer, Nadine Radford, said during a July hearing.
Ali, Sarwar and Hussain pleaded guilty tokistan, was one of the key organizers of the airliner plot.
Al-Masri, who officials say died of hepatitis in Pakistan last December, is also suspected of having a role in orchestrating the July 7, 2005 bombing attacks on London transit, which killed 52 subway and bus commuters.
Rashid Rauf, a British-born baker's son - was a key link between the U.K. and militants in Pakistan and Afghanistan and arrested soon after al-Masri give the final go-ahead, officials said A former university roommate of Gulzar, he escaped from Pakistani police guards in December and is still at large. British officials want to question him over the 2002 murder of his uncle Mohammed Saeed in central England.
Security officials remain convinced that al-Qaida and other terror networks are still obsessed with airline plots because of the potential death tolls and spectacular nature of such attacks.
The jury in the case of three men accused of helping to plan the July 7, 2005, London transit bombings was dismissed in August after failing to reach a verdict. Prosecutors said at the time that they wanted a retrial of Waheed Ali, Sadeer Saleem, and Mohammed Shakil - the only people charged over the attacks on the British capital's transit network.
