Prince William landed an air force helicopter at the home of his girlfriend's parents during a training flight, Britain's Defence Ministry said Sunday.
British media called the exercise wasteful at a time when the military is stretched by wars in Iraq and Afghanistan and warned it risked testing the public's patience with the monarchy.
The landing on the family farm of Kate Middleton on April 3 was planned and authorized as part of the prince's Royal Air Force pilot training, the ministry statement said.
"The aircraft landed in the field, after taking all necessary safety precautions, and was on the ground for 20 seconds," the ministry said. "No one got on or off the aircraft."
The military lacks landing sites and often seeks permission from landowners to use their fields for training exercises, the statement said.
The prince and Middleton have dated since they were students at St. Andrews University in Scotland.