The Multilateration (MLAT) is a new surveillance system which has been introduced worldwide for air traffic control. This paper describes evaluation results of MLAT for airport surface surveillance conducted at Sendai airport and Tokyo international airport. Moreover, causes of performance degradation and mitigation means for the degradation are also described. A main point of this paper is to focus relations between performance and antenna allocations based on the evaluation results.
Increasing aviation demand has brought expansions of major airports. As a result, the airport layout and operations have become more complex. In order to ensure safe and smooth operations in this situation, an essential requirement is provision of accurate and highly reliable surveillance information to air traffic controllers. And this requirement needs to introduce an advanced surveillance system, such as MLAT.
MLAT detects signals of SSR transponders (Secondary Surveillance Radar), and measures a target position by the TDOA technique (Time Difference of Arrival). To achieve high performance and high reliability in MLAT, the most important factor is an ideal antenna allocation based on the airport layout. And installing antennas to appropriate positions is also important to avoid performance degradation by signal interference.
Electronic Navigation Research Institute has conducted various performance evaluations of MLAT by using an evaluation system at Sendai airport and Tokyo international airport. The evaluation at Sendai airport is basic tests to confirm functions and performance of the evaluation system. Main purposes of the evaluation at Tokyo international airport are to verify performance and to propose optimal antenna allocations based on the test results. This paper points out some problems confirmed by the evaluation, such as restrictions for antenna height. The restrictions bring signal corruption by interference, and therefore, may lead to performance degradation. In addition, this paper provides mitigation means for the performance degradation by improving antenna allocations and installation positions of antennas. The evaluation results indicated that the mitigation means are effective to achieve better performance.
