On the afternoon of May 12, two remote sensing aircraft from the Chinese Academy of Sciences' Center for Earth Observation and Digital Earth were placed on standby in the Wenchuan earthquake disaster area. At 14:08, the No. 1 remote sensing aircraft equipped with optical ADS80 took off; at 14:17, the No. 2 remote sensing aircraft equipped with SAR sensors took off. The two aircraft acquired data according to the predetermined airspace. Due to cloudy weather over most areas of the measuring zone that day, it was difficult to acquire optical remote sensing data; the No. 2 aircraft acquired data around the new sites of An County and Beichuan County, covering an area of about 40 square kilometers.