A Real-Time GPS Spoofing Detection and Mitigation Framework for Civil Aviation Using Anchor Selection and WGDOP

Abstract

Global Navigation Satellite System (GNSS) signals are the primary source of positioning, navigation and timing information in civil aviation. The open structure of civil GPS signals makes them inherently vulnerable to spoofing, and reported incidents affecting commercial aircraft have increased sharply since September 2023. Existing countermeasures either detect spoofing without restoring the navigation solution, depend on dedicated antenna arrays, or require offline training data, so none of them simultaneously satisfies the operational constraints of a standard single-antenna airborne receiver. This paper proposes a hardware-free, real-time framework that combines received signal power analysis with an Anchor Selection Method (ASM) and Weighted Geometric Dilution of Precision (WGDOP). Free-space path loss, received signal power and carrier-to-noise density ratio are derived from native receiver observables and compared against thresholds established from 260 nominal epochs in order to flag spoofed pseudoranges. The remaining authentic satellites are then enumerated exhaustively, and the subset that minimises WGDOP is adopted as the optimal anchor set for a linear least-squares position solution. The framework was evaluated using real-time aircraft trajectories obtained from Flightradar24 together with GPS satellite positions obtained from N2YO.com, covering 26 commercial flights operating in the Baghdad Flight Information Region and yielding 1,386 independent spoofing trials. The proposed identifier achieved an overall accuracy of 0.9929, a sensitivity of 0.9473 and a specificity of 1.0000, with no false alarms recorded. After correction, the average positioning root mean square error fell from 7,888.823 km to 166.6875 km, a reduction of approximately 97.89 %, while the average geometric dilution of precision converged to 0.9994. The results indicate that real-time spoofing detection and pseudorange correction can be achieved on standard avionics receivers without additional hardware, external infrastructure or training data.