Abstract: A polysiloxane copolymer composition comprises: a polysiloxane unit comprising 4 to 50 siloxane units, and a polyester-polycarbonate unit consisting of 50 to 100 mole percent of arylate ester units, less than 50 mole percent aromatic carbonate units, less than 30 mole percent resorcinol carbonate units, and less than 35 mole percent bisphenol carbonate units, wherein the siloxane units are present in the polysiloxane unit in an amount of 0.2 to 10 wt % of the total weight of the polysiloxane copolymer composition, and wherein the polysiloxane copolymer composition has a 2 minute integrated heat release rate of less than or equal to 65 kilowatt-minutes per square meter (kW-min/m2) and a peak heat release rate of less than 65 kilowatts per square meter (kW/m2) as measured using the method of FAR F25.4, in accordance with Federal Aviation Regulation FAR 25.853 (d). A window article for an aircraft, comprising the polysiloxane copolymer composition, is also disclosed.