On 25 May, the flight took off at 2:50pm local time for the 1 hour 20 minutes flight to Hong Kong.
About 20 minutes after takeoff, the aircraft disappeared from radar screens, suggesting the aircraft had experienced an in flight breakup at FL350, near the Penghu Islands at Taiwan Strait, killing all 19 crew members and 206 passengers. 190 of the deceased are Taiwanese, 14 Hong Konger, 1 Singaporean, 9 Mainlanderss, and 1 Swede. 3 were infants. 114 were in a group tour organized by five travel agencies to Hong Kong or Mainland. The plane was expected to arrive at 4:28 PM.
At 5:05 P.M., a military aircraft C130 was spotted 20 nautical miles northeast of Makung. Oil slicks were also spotted at 5:05 PM. The first body was found in 6:10 PM.
Searchers have recovered 162 bodies and 15 percent of the wreckage, including part of the cockpit, and have found no signs of burns or of any explosives or gunshots
There was no distress signal or communications was sent out prior to the crash. Radar data suggests that the aircraft broke into four pieces while at FL350. This theory is supported by the fact that articles which would have been found inside the aircraft (magazines, etc.) were found up to 80 miles from the crash site. The weather and climate were normal. The CVR showed that pilot did not detect any anomaly and was humming the famous oldie tune "When Shall You Return?" (何日君再来) by Teresa Teng.
The flight data recorder from Flight 611 shows that the plane began gaining altitude at a significantly faster rate in the 27 seconds before the plane broke apart, although the extra gain in altitude was well within the plane's design limits. The plane was supposed to be leveling off then as it approached its cruising altitude of 35,000 feet. Shortly before the breakup, one of the aircraft's four engines began providing slightly less thrust. By coincidence, the same engine is the only one that has been recovered so far from the sea floor.
The China Airlines representative said it was due to "fatigue of the metal", which maintenance could not have picked up. Some families of crash victims have accused the airline for keeping a 23 years old plane in service.