With enough room to fit 245 passengers, the American Airlines flight made the nine-hour trip on 22,000 gallons of fuel - a total of 4,400 gallons per passenger.
However, the lucky five passengers were treated to a luxury flight from Chicago to Heathrow when they were upgraded to business class and were waited on by two cabin staff each.
American Airlines came under criticism when the flew a Boeing 777 with just five passengers on board
But each passenger on the plane had a massive carbon footprint of 43.2 tonnes of CO2 and it has been branded one of the worst "environmental crimes".
The flight had been fully-booked, but an 11-hour delay due to a mechanical failure meant most passengers made other travel arrangements.
Richard Dyer, of Friends of the Earth, said: "Flying a virtually empty plane is an obscene waste of fuel.
"Through no fault of their own, each passenger's carbon footprint for this flight is about 45 times what it would have been if the plane had been full."
The average car would have to drive 123,000 miles to clock up the same carbon footprint or a British household would five years to use up the same amount in gas and electricity.
Environmentalists have reacted angrily to the airline's decision.
Campaigners said it was an obscene environmental crime and was the worst case of its kind they had come across.
Rather than cancel the near-empty flight AA90, American Airlines decided to go ahead with the controversial trip went ahead as more passengers were waiting at Heathrow for the plane to arrive.
Norman Baker MP, the Liberal Democrat spokesman for transport, said: "I have heard of planes flying at two thirds full before but this is the worst example I have come across.
"It is a climate change crime. It shows the ludicrous nature of the aviation industry.
"For an airline to think it sensible to fly aeroplanes which are virtually empty and where the crew outnumber the passengers is madness.
"I hate to think of the size of each passenger's carbon footprint on that flight.
"I understand the airline has a timetable to stick to and you can't leave people stranded but I can't believe there wasn't an alternative rather than fly a near-empty plane across the Atlantic."
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Anita Goldsmith, for Greenpeace, accused the US airline of putting profit before the environment.
She said: "Aviation is the fastest growing source of climate changing emissions, yet here we have another example of the reckless approach the industry takes when it comes to a choice between profit and convenience over the environment and all our futures."
Environmentalists have been campaigning for the government to force airlines to pay for carbon offsetting rather than passing it on to passengers.
Mr Baker said: "This case shows the need for the aviation industry to pay its own tax on fuel rather than the passenger which would give companies the incentive to fill their planes."
Mr Dyer, of Friends of the Earth, added: "Governments must stop granting the aviation industry the unfair privileges that allow this to happen by taxing aviation fuel and including emissions from aviation in international agreements to tackle climate change."
Flight AA90 had been due to take off from Chicago's O'Hare International airport at 3.10pm on Friday, February 8.
It did not leave until after 5am the next day and arrived in London at 5pm.
Anneliese Morris, spokeswoman for American Airlines, said they thought long and hard about cancelling the flight but did not due to the number of passengers waiting in London.
She said: "This situation is very rare. Exceptional operational circumstances meant that we had to operate this flight from Chicago to London with just five passengers on board.
"The flight operated with a full complement of crew as they had to position in London to operate one of the flights back to the US.
"The decision to do so is never taken lightly, but we had to consider the knock-on impact cancelling this flight would have had on our schedule out of London on a weekend when all of the flights were extremely busy.
"Our goal is to operate our fleet as efficiently as possible to provide our customers with excellent service while being a responsible environmental citizen."
David Learmount, of Flight International magazine, said that had American Airlines cancelled flight AA90 it would have taken days to transfer the Heathrow passengers onto other planes.
He said: "The average load factor across the Atlantic is 88 per cent, that is every plane flying between the US and the UK is 88 per cent full.
"To transfer 250 passengers onto other planes would take days to clear the flight, because there will be five passengers on one plane here and 10 on another there.
"The bulk of the passengers will spend two or three days stuck in a hotel being paid for by the airline."
© 2008 The Daily Mail