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) success rate when attacking the flock, rather than increasing the ability of the flock to spot an approaching predator. By birds co-existing with one another in a flock, less time and energy is spent searching for predators. This mutual protection of one another within the flock is one of the benefits to living within a group. However, as flock numbers increase the more aggressive individuals within the flock become towards one another. This is one of the costs to living within a flock. It is often seen that flocks are dynamic and thus fluctuate in size depending on the needs