b'Minerals geophysics radiometrics and emerging AEM. OtherDuring acquisition, the flights mustGravity gradient acquisition systems jurisdictions, such as the USA, leave themeet guidelines as to height aboveall derive from the original Lockheed data in the hands of individuals, andground, deviation from the originalMartin GGI pack. Figure 1 shows a Falcon consequently lag in an obvious way anyflight plans, speed and accelerationssurvey from Victoria being subjected to a attempts at upscaling their geologicalof aircraft, and turbulence with thenoise review. In the case of AEM surveys, mapping and making predictions aboutcontinuous recording history for eachincreasingly both X and Z components what lies undercover. instrument remaining within operationalof the B-field decay curve responses There is typically a lag of many yearsspecifications. Required noise levels,are deliverables. For such systems, all between an initial geophysical surveycalibrations, data corrections andimportant issues are calibrations of both and follow up drilling, ground samplingreduction and their specifications asX and Z so that they are consistent with for geochemical purposes, and detailwell as processing requirements haveeach other, lag distances, rotational state structural geology studies. So, airbornedeveloped over decades mainly byof the bird and non-saturation of the geophysics is the common path finder.government institutions and, obviously,sensors in the instrumentation.As there are many competing technicalby contractors. The human factorand safety requirements and engineeringPrecisionproducts, there is a spread of qualityAs many as 50% of all airborne produced by the available systems. GoodAs it turns out, most instruments that aregeophysical surveys that are currently practice is stated in terms of flying height,used have relatively limited precision,being flown have issues that are left speed of flying, topographic drapes andoften because data are recorded with,unresolved when the survey is accepted line spacing. These requirements varysay, no more than 24 bits at best (so 4and paid for.from one physical parameter to anotheror 5 digits). Some of the measures areThere is an ever-rising specifications bar - see Reid, (1980). Clifton (2016) buildsless well constrained, particularly thefor each of the survey types that tries on this original work and develops theinstantaneous rotational state. Do notto counter issues that have occurred in arguments for flight line spacing andbe confused by the quoted number ofthe past, but were accepted previously direction, to create survey data that isdecimal places, as these may not reflectand are now deemed unacceptable. better suited for the purpose of deducingthe actual precision of the originalIf there is not an independent QA/QC near surface buried bodies in terms ofmeasurement. Gamma ray data areprocess being employed on a survey detectability. The goal posts have shiftedcollected as counts/second in energyusing appropriate checks, it follows towards not just a surface mappingwidows from 0 to 3 million electron voltsthat there is more likelihood of inferior outcome but finding out more about(MEV). You may not get any counts at allresults even if there are the requisite the features in the top 1000 m belowin some of the channels, so knowledgepretty pictures. Airborne geophysical the topography. Consequently, whenof the Poisson distribution is used to findsurveys are one of the prime techniques designing a new geophysics airborneand recover signal amongst the noise. available to illuminate the near surface acquisition system, no one system designIf a vector or tensor gradient are beinggeology, even if indirectly. The various is optimal for all cases. measured, or a secondary field, thegovernment agencies in Australia are Also, commercial competition has provenrotational state of the instrumentationcollectively spending more than $100m to be very important as an evolutionarysystem is critical. annually.driver in that the value for money proposition drives one aspect of the technology, versus the requirement for highest quality and a multi-sensor system to illuminate the unknown and lead to a better geology interpretation.When a new technology emerges and is championed by an exclusive development partner, e.g. magnetic tensor gradients, the progress of the development can struggle to progress as fast as a more competitive environment is capable of (FitzGerald, 2013).Method and resultsField acquisition issuesBefore a survey is undertaken, a process of survey design is undertaken that is affected by the weather, availability of aircraft, and fuel. Initial test flights are undertaken to verify that airborne systems are functioning by flying repeatFigure 1.Falcon Gravity Gradient - 3 channel noise image: Local StdDev (600 m) of AB_NE-diff, AB_UV-diff lines. and Turbulence in R-G-BAPRIL 2020 PREVIEW 36'