Jet engines have to be designed to withstand the ingestion of birds of a specified weight and number and to not lose more than a specified amount of thrust . The weight and numbers of birds that can be ingested without hazarding the safe flight of the aircraft are related to the engine intake area . The hazards of ingesting birds beyond the " designed-for " limit were shown on US Airways Flight 1549 when the aircraft struck Canada geese
US Airways Flight 1549
US Airways Flight 1549
Aviation safety