Geomagnetic Study for Determination of the Compass Calibration Site Suitability at the Sofia Airport

Despite the presence of modern electronic devices aeronautics still needs of magnetic compasses as a primary direction indicators on small aircrafts and as very important back-up devices on larger airplanes. Airports infrastructure must include elements which allowed an aircraft check to be performed, and to calibrate or compensate onboard compasses (Rasson, 2006). Main task of the present research is to determine the suitability of the north deicing pad of the Sofia airport to be used as a calibration site for backup compass systems of Airbus 320 and Boeing 737 airplanes. For this purpose two types of investigations have been performed: 1) magnetic total field intensity measurements and 2) magnetic declination measurements. Analysis of the obtained results showed the influence of located magnetic disturbers and outlined the homogeneous enough zone for performing aircraft compass calibration procedures.