The ground-to-air communications in the aircraft approach stage suffer from multipath fading. We propose to combat this problem using cooperative communication technique. The relay selection problem is formulated to minimize the spectrum cost while preserving the signal-to-noise-ratio (SNR) outage requirement of the approaching aircraft. By leveraging the position and velocity information in the automatic dependent surveillance-broadcast messages, the average channel gains can be derived with uncertainty sets based on the Ricean channel model. Because the outage probability of the received SNR is intractable, we transform the outage constraint into a simple but efficient reliability requirement. The formulated problem is a mixed integer nonlinear optimization problem, with robustness in the worst-case average SNR. A robust greedy relay selection algorithm is proposed as a solution, whereby a Kalman filter based trace prediction algorithm is adopted to determine the order of relays. Simulation results are given to show the effectiveness of the proposed scheme. -B of the aircraft under serious weather condition, the synthetic vision system (SVS) [2] has been developed to extend the visual range of the pilot. The SVS can integrate the position information from global positioning system and inertial navigation system with the traffic information from the control tower, which are displayed on the screen to help the pilot make decisions. In SVS, data link technology is adopted for the signal transmission from the control tower to the approaching aircraft. However, because of the high speed and low elevation of the approaching aircraft, the performance of point-to-point data link suffers from serious multipath fading in the flight test [3,4].In the last decade, cooperative communication technique has received much attention in the communication society [5][6][7], which is proved to be effective in combating multipath fading by exploiting the spatial diversity of the relay nodes. In our work, we consider the application of cooperative communication technique in the aircraft approach scenario. Considering the requirement RELAY SELECTION FOR COOPERATIVE COMMUNICATIONS IN AIRCRAFT APPROACH 115 ‡ Straight-in approach means the final approach has begun without first executing a procedure turn, and the trace of the aircraft approach follows the extended runway centerline. In fact, the approaching pattern only determines the mobility pattern of the aircrafts. The analysis and algorithm in our paper still work under other approaching patterns. § The simulation is conducted on MATLAB 7.0.1, where the system configurations are : Intel(R) Core(TM)2 Duo CPU E7200@2.53GHz, 2G RAM, 32bit OS.