An article in the April 8, 2010 edition of Nature explores the way in which flocks of birds move together while flying in formation. Scientists mounted 16 gram GPS loggers on the back of homing pigeons in order to track the flight of each bird in a flock of up to ten birds.

The experimenters found that the bird’s position in the flock during flight depended upon a defined social hierarchy-an airborne pecking order. They also found that each bird responded more quickly to a flock mate seen with the left eye, an observation  supporting the theory that each bird has a specific role depending on its position in the flock formation.

Conservation Magazine, in the January-March 2010 issue, reprinted an article from the Economist. The Economist noted a study preformed by a group of researchers from Stanford University led by Illan Kroo which highlighted the possibility that airplanes might save on fuel if they mimicked the flight pattern of birds flying in formation.

Birds flying in formation expend less energy than those who are not in formation. The air that flows over the bird’s wings curls upward behind their wingtips, a phenomenon known as up wash. Birds flying in the up wash experience less drag and spend less energy on propelling themselves than those not in the up wash. Aeronautics expert Peter Lissaman has speculated that a formation of 25 birds might increase their range of flight by almost 71 % because of this phenomenon.

Kroo and his colleagues modelled these principles to the flight of aircraft. The model scenario postualted three passenger jets leaving from Las Vegas, Los Angeles, and San Francisco and then rendezvousing over Utah to continue their respective flights to London in an inverted V formation. According to the model the three aircraft would use 15 % less fuel than if they continued alone and would at the same time reduce their CO2 emission and  nitrogen oxide emissions substantially

Would passengers feel uncomfortable flying in a convoy? The planes could fly separated by several nautical miles, so a passenger looking out the window of one plane might not even see the other planes. Weather will have an effect. In zones of turbulent air the wake of the airplanes will decay more quickly than in calm air and the up wash effect will diminish. Scheduling commercial airlines to fly in a mini flock might also be difficult. The idea might have more application to the flight of military and cargo planes which do not have to meet advertised commercial schedules. The article ends by noting that the Defense Advanced Research Projects Agency is already investigating the possibility of formation flights, so that the next flock you hear flying overhead may be airplanes rather than birds.