With the opening of Heathrow's Terminal Five, and plans for the airport's third runway at the decision stages, the debate over the sustainability of air travel has never been higher on the agenda. So, it was a very bad time for it to emerge that British budget airline Flybe has been flying fake passengers in order to avoid fines for missing targets.

The airline had contractual traffic targets for its Norwich to Dublin route. Rather than risk the £280,000 penalty for missing its commercial obligations, Flybe advertised for actors to fly the route instead.

Under the route agreement with the regional airport, Flybe was to transport 15,000 people between Norwich and Dublin in the 2007/2008 financial year. As the March 31st deadline approached, Flybe realised they were 172 passengers short. So, they gave away 200 free tickets, briefed staff that they may have to fly to Dublin, and placed an ad with an extras agency. The ad read "extras aged 16+ needed for paid work flying to Dublin", offered £80 a day, and added that actors may need to fly three flights in a day.

Although the actors were not needed in the end, it has emerged that airline staff were flown to Norwich just so they can then be flown to Dublin and back to make up the quotas. So, a guideline that is supposed to prevent airlines from flying with empty seats ended up with an airline paying people to fly. And this comes from an company that claims to be "at the forefront of the efforts by airlines to reduce the environmental impact of air travel and promote sustainable growth in the aviation industry."

A spokesman for Flybe admitted the move was "unusual", and promised that free seats would be carbon offset. Environmental campaigners lined up to criticize the airline however, with Friends of the Earth's Tony Bosworth denouncing the "Alice-in-Wonderland economics of the aviation industry." FOE are now calling on the government to urgently investigate quota practices around air travel.