SHANGHAI—When civil aviation experts from around Asia huddled in January to study how they might coordinate search-and-rescue following an ocean plane crash, China's government sent word that it lacked a response program but didn't dispatch anyone to attend.

Still, just over a month later, China's government mounted a full-throttle response to the disappearance of Beijing-bound Malaysia Airlines Flight 370 by sending planes and ships to the search area. Noting that more than half the 239 people on the March 8 flight were nationals...