Compressor stall The airliner successfully made a forced landing in a forest clearing without loss of life. On January 15, 2009, US Airways Flight 1549, an Airbus A320, ditched in the Hudson River about five minutes after takeoff. The apparent cause was compressor stall in both CFM International CFM56-5B engines after flying through a flock of birds about 90 seconds after takeoff. This same aircraft may have suffered a compressor stall on the right engine two days earlier. After an incident in which an Airbus A321-200 experienced compressor stalls on both engines during initial climbout on December 15, 2008, an EASA Emergency
Flock (birds) to find a reliable food source will alert the flock and the entire group may benefit by this finding. While this is an obvious benefit of the information-sharing model, the cost is that the social hierarchy of the flock may result in subordinate birds being denied food by those that are dominant. Another cost is the possibility that some individuals may refuse to contribute in the search of food and instead simply wait for another member to find a food resource. These individuals are known as producers and scroungers, respectively. An intricate hunting system can be seen in the Harris's