a jet engine. It is a common aircraft safety hazard and has caused fatal accidents. In 1988 an Ethiopian Airlines Boeing 737 ingested pigeons into both engines during take-off and then crashed in an attempt to return to the Bahir Dar airport; of the 104 people aboard, 35 died and 21 were injured. In another incident in 1995, a Dassault Falcon 20 crashed at a Paris airport during an emergency landing attempt after ingesting lapwings into an engine, which caused an engine failure and a fire in the airplane fuselage; all 10 people on board were killed. 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. In 2009, an Airbus A320 aircraft, US Airways Flight 1549, ingested one Canada goose into each engine. The plane ditched in the Hudson River after taking off from LaGuardia International Airport in New York City. There were no fatalities. The incident illustrated the hazards of ingesting birds beyond the "designed-for" limit. The outcome of an ingestion event and whether it causes an accident, be it on a small fast plane, such as military jet fighters, or a large transport, depends on the number and weight of birds and where they strike the fan blade span or the nose cone. Core damage usually results with impacts near the blade root or on the nose cone. Few birds fly high, so the greatest risk of a bird ingestion is during takeoff and landing and during low level flying. Volcanic ash If a jet plane is flying through air contaminated with volcanic ash, there is risk that ingested ash will cause erosion damage to the compressor blades, blockage of fuel nozzle air holes and blockage of the turbine cooling passages. Some of these effects may cause the engine to surge or flame-out during the flight. Re-lights are usually successful after flame-outs but with considerable loss of altitude. It was the case of British Airways Flight 9 which flew through volcanic dust at 37,000 ft. All 4 engines flamed out and re-light attempts were successful at about 13,000 ft. Uncontained failures One class of failure that has caused accidents is the uncontained failure,