Shall we try to raise this debate a little higher?
Most airlines use computer flight planning that calculates the cost of all routes between departure and destination and produces the cheapest, taking into account forecast winds, operating costs and overflight charges. Some days the winds favour one route, some days another. If the prime route encounters significant delays the airline will use the less optimum route to avoid delays and pictures on the 6 o'clock news of stranded passengers.
What I find rather strange is the BBC use of helicopters. I remember about a year ago they had the whole BBC news team up in Scotland with a wild and speculative piece about bird-flu and a couple of swans. We were all treated to the spectacle of the news presenter doing the news live from a helicopter. Needless to say the swans didn't have bird-flu and the story died. Now is there a lesson in carbon footprints in that wild "goose" chase?