THE RELIABILITY OF AIRPLANE ATTITUDE DETERMINATION USING THE MAIN GEOMAGNETIC-FIELD WITH APPLICATION TO TENSOR VLF DATA-ANALYSIS

The attitude angles of an aeroplane used for geophysical measurements are necessary in order to calculate field components in a fixed refere nce frame. In this paper it is shown analytically how the measurement of static magnetic field components can be used to determine the attit ude angles. Error analysis shows that when magnetic anomalies are smal l to moderate (less than 5% of the total field), the attitude angles c an be determined to within a few degrees at high latitudes. For a give n area the maximum error is linearly related to the magnitude of the a nomaly. The technique is illustrated on a tensor VLF data set from an area in Sweden with local magnetic anomalies less than 1% of the regio nal total magnetic field. Attitude errors propagated into tensor VLF t ransfer functions are of the same order as their random errors.