Science: Birds v. Planes

Collisions between planes and birds are reported by U.S. airline pilots about twice a week. They can disable wing tips, dent the fuselage, foul the motor—but the chief danger is a windshield break. Last month a DC-3 almost crashed in Iowa when a duck came through the windshield in an explosion of glass and feathers and knocked out the pilot (the copilot saved the plane).

Both airmen and ornithologists think that bird collisions may have been responsible for some unsolved air disasters. The bird-bumping problem is becoming So troublesome that airlines rate the Civil Aeronautics Administration’s windshield-strengthening experiments (TIME, Feb. 22, 1943) as the most urgent present research project.

In the October Air Transport, a veteran airlines pilot, Pat Curtin, tells some of the airmen’s strange stories about migrating birds. Most collisions occur at night or in clouds, when both planes and birds are flying blind. Migrating birds usually fly at night, stopping to feed in daylight. Ornithologists agree that they seem to have a sixth sense which enables them to fly even in “instrument weather.” Curtin says that one pilot, chasing flocks of ducks, has seen them take cover in clouds. Once a covey flew round & round inside a small cloud while he circled it in his plane.

A Sense of Altitude. Another Curtin story suggests that birds, like planes, may be downed by wing-icing: a pilot reported that one night, after he had been forced down at Portage, Wis., hundreds of mallard ducks also landed in the streets of the town, their wings heavily ice-coated.

The chief U.S. expert on migratory birds, Frederick C. Lincoln of the Fish and Wildlife Service, doubts such stories; he admits that birds are sometimes forced down by snowstorms, but thinks confusion and fright have as much to do with it as anything. Nonetheless, airmen’s reports have greatly extended ornithology. Airmen, for example, have found old notions about the speed of birds much exaggerated: the top speed of ducks seems to be about 55 m.p.h.; of the fastest known birds, swifts and duck hawks, not more than 150 to 200 m.p.h.

Migrating birds generally fly at less than 3,000 ft. above ground level, but in getting over mountains ducks have been known to reach 7,500 ft. above sea level, cranes and condors, 20,000 ft. Highest recorded bird altitude (reached by a flock of geese photographed in India): 29,000 ft. Ornithologists believe that birds may be helped in blind flying by a brain mechanism sensitive to changes in altitude.

By now, airmen have located the areas of greatest danger from flying birds. The migrations follow fixed routes; the heaviest traffic is up & down the Mississippi-Missouri Valley. Duck strikes are most frequent, but flyers do not fear them as much as certain heavier birds. A 15-lb. goose, flying at 50 m.p.h., colliding head on with a 200-m.p.h. plane, can do formidable damage.

Pilot Curtin has noticed that birds seem to seek the altitude where they get the most favorable tail winds. His suggestion: let the airlines take soundings to determine how high the birds are flying, then route their planes along other levels.