Radar Detection, Tracking and Warning of Avian Targets at Airports - Reporting of potentially hazardous bird presence at airports using low cost magnetron Moving Target Detector (MTD) radar

Abstract

During the last years, Radian AS has been working on new methods for improving the detection capability of the standard civil marine radar. A coherent-on-receive radar demonstrator with a PC-based platform has been developed and the methods are found well suited for detecting small moving targets over land and sea. An operational birdstrike (aircraft-bird collision) avoidance radar system based on this technology has recently been deployed at Værnes Airport, Norway. This system uses a slightly modified civil marine radar, a computer and methods of detection based on a Moving Target Detector (MTD) processor. The resulting radar video is broadcast to the airport s Air Traffic Control (ATC) Tower to allow initiation of precautionary measures. Since the current system demands manual interpretation and constant monitoring of the MTD radar video, there is need for an Automatic Detection and Tracking (ADT) system and a warning system that draws attention to specific situations.

In this Master s Thesis, methods for radar detection, tracking and Early Warning (EW) of avian targets at airports are investigated. The work is based on theoretical analysis, testing with real radar measurements and simulation that incorporates real measurements. The methods of detection are improved by modification of the MTD processor. A specialized, batch-processing tracker called a Bird Flight Path Detector (BFPD) Tracker is developed and implemented to automatically identify and track birds in the airport vicinity. An EW functionality is also developed and implemented to monitor the resulting tracking data and give warning of potentially hazardous situations in advance. Furthermore, the performance of the proposed tracker and the resulting total system is optimized, analyzed and evaluated.

The detection capability of the radar is found sufficient for use in a birdstrike avoidance application. According to performed theoretical calculations, the existing radar system is able to detect a single goose at about 4 km with a probability of detection of P_d = 0.7 and a probability of false alarm of P_fa = 0.001. Testing shows that in practice, multiple flocks (of varying numbers) of geese are detected consistently enough to allow continuous tracking by the BFPD Tracker up to about 4 km in range over both land and sea. It is also shown that the BFPD Tracker is be able to identify and follow all of the important bird presence while simultaneously exhibiting a probability of true (caused by birds) confirmed track establishment around 70% and a probability of true batch association around 96-100%. The latter is hence a good indicator of true bird presence. Simulation experiments show that the total system is able to detect an avian target roughly the size of a single goose at ranges of about 3 km with P_d = 0.875 and P_fa = 0.001. Simulation also shows that the BFPD Tracker is able to track this target continuously up to 4 km over sea with an RMS error of 2.37 m in range, 0.084 in azimuth and 1.64 m/s in velocity.

The EW functionality is found capable of identifying and giving warning of almost all manually identified potentially hazardous situations while showing a very low probability of false warning (<< 1%). Long-term testing and corresponding knowledge of the true bird activity is needed to accurately estimate the probability of false warning, but this work indicates that the BFPD Tracker and EW function is suited for tracking and EW application in an ATC Tower. Near real-time processing is deemed feasible with standard computing hardware and if the system is developed further it may help mitigate overall birdstrike risk and contribute to improved safety in aviation.