BP Exploration Company Ltd Research Unit (Sunbury, England) flew an airborne laser fluorosensor (ALF) survey over the Great Australian Bight region during the period January-March 1990, as part of BP Australia Ltd's Australian continental shelf regional petroleum prospectivity evaluation. The survey was timed to coincide with an expected offshore acreage licensing round. A total of 27,624 line kms of production were recorded in 56 sorties, and covered an area of approximately 108,508 square kms at a 5 km line spacing. The survey was designed to detect occurrences of oil suspensions and slicks at the sea surface, arising from natural seepage of petroleum. Currently in the offshore remote sensing industry no proven, operational technology exists which can systematically confirm the presence of hydrocarbons in the subsurface. The ALF tool is a new experimental technology undergoing trials worldwide by BP, who are further developing the method as a safe, broad-scale offshore exploration technique. An aircraft-mounted excimer laser directs a pulsed beam of light of 308 nm wavelength at the sea surface, exciting characteristic ultraviolet photoemissions from any oil film which may be present. The induced fluorescence, which may vary in character and distribution from basin to basin, is collected aboard the aircraft by a high efficiency telescope and its frequency spectrum is analysed and converted to digital electrical signals by a special, proprietary detector incorporating BP's experimental timing and synchronisation circuitry. Only 2 definite fluors were detected during the entire ALF survey, both of which are classed as weak. They probably indicate leakage from poorly sealing hydrocarbon traps, but could also be simple manifestations of hydrocarbon generation (i.e. migration end-points), or of secondary migration from a petroleum accumulation. Sea state during the survey was predominantly calm, and the quality of data obtained is regarded as good. Overall 32 fluorescence anomalies were identified, but almost all of them gave signals too small to allow confirmation as a fluor, based on other trial experience, nor could they be significantly correlated with subsurface structures known from previous geophysical and geological exploration. Accordingly, in BP's estimation, the petroleum potential of the Bight region does not warrant upgrading based on the results of this investigation. Consequently the company did not bid for any of the 5 Great Australian Bight vacant blocks gazetted by the Commonwealth in May 1990 as available for grant of petroleum exploration permits until 26 October 1990.