Speedy Aeromagnetic Detection Technology for Underwater Heritage Sites: A Case Study of the Flying Tigers P40 Wrecked Aircraft

80 years ago, a U.S. Flying Tigers P40 jet was crashed in the Dianchi Lake. This letter introduces the applicability of aeromagnetic detection technology for such underwater cultural relics. In this study, a magnetic detection system is used to sweep over the suspected lake area of the Dianchi Lake. The obtained magnetic anomaly fingerprint curves are mapped to get the magnetic images in geographical coordinates. It took 10 min to scan the 14000 m2 area and 1 min to process the data. In particular, the airplane ruins are buried in the soil layer at the bottom of the lake. In the survey, the system was flying at a height of 3 m above the lake, which is 6 m deep. It results in a magnetic anomaly strength of 30 nT and an estimated latitude-longitude identification of (E $102.^{\ast \ast \ast \ast }0$ , N $24.^{\ast \ast \ast \ast }2$ ). The research results indicate that the aeromagnetic detection technology shows good estimation accuracy on underwater cultural relic sites.