Why would an airline be prepared to run hundreds of flights at a total loss? Environmental campaigners, embroiled in their green agendas, are outraged that British Mediterranean Airways (BMed) has been flying an empty 124 seat Airbus jet between Cardiff and Heathrow six times a week simply in order to keep a grip on its allocated slot. An airline needs to make at least 80% use of its allocation over a six-month session to preserve the entitlement or it risks seeing its rivals take over the slot.

Friends of the Earth's transport campaigner Richard Dyer said: "You have a very polluting aircraft flying empty when the airline has not paid duty on fuel and has no passengers to pay taxes. Any system that encourages this needs to be reformed. It does cast a bit of doubt about the airline industry and how they are trying to clean up their act. It is only one airline but it is a situation where it seems profits come before the environment." FOE claim that: "each 140-mile flight pumps out 5.21 tons of carbon dioxide. Over the five months it would have contributed the equivalent of the annual carbon emissions of a 2,000 home town."

BMed flies to 17 destinations throughout Africa, the Middle East and Central Asia with its eight aircraft, and says it will start using the slot again for commercial flights in April 2007. It plans a new service for the empty slot after suspending flights to the central Asian republic of Uzbekistan in October following civil unrest there. It is evidently nothing less than a matter of commercial economics. Slots at Heathrow have been sold for as much as $20 million.

From the Blogosphere, we have the following counters:
"The 140-mile flight between Heathrow and Cardiff emits 5.2 tonnes of carbon dioxide?"
Carbon (from the fuel) atomic mass 12
Oxygen (from the air) atomic mass 16
So more than two thirds of the mass of the carbon dioxide comes from the air the fuel is burnt in. Making an assumption of jet fuel being C16H34 (heavy end of the range), 1.66 tonnes of fuel certainly would emit 5.2 tonnes of CO2. However, by comparison, the three week early switch to daylight savings time in the USA and Canada (except for Saskatchewan) has saved 279 billion cubic feet of natural gas, and avoided nearly 10.8 million metric tons of carbon emissions.

Nevertheless the last empty-heading (vs "dead-heading") airline that did this had the decency to use a small Beech aircraft rather than a jet.