Middleton, 26, and her parents Michael and Carole are believed by British newspaper reports to have watched as he maneuvered the 90-foot, twin-rotor, troop-carrying Chinook into position.
He was only on the ground in his aircraft for 20 seconds, a source tells PEOPLE, but that was enough to draw criticism of the sortie as a waste of taxpayers' money. The News of the World called him a "show off" and ran the headline "Outrage as Wills Lands in Kate's Garden."
On Monday, the Ministry of Defense rushed to William's aid saying this was part of his ongoing instruction. "This was very much a routine training sortie that achieved essential training objectives," a spokesman says. "[It] was fully authorized and planned and was an agreed part of Prince William's attachment to the RAF."
Permission to LandWilliam, who had been based at RAF Odiham about 16 miles away, was conducting battlefield helicopter routines, which meant an orbit of a landing zone at around 300 feet before coming down to land.
Apparently, there are only two fields near the base where the helicopters can attempt this, and, with neighbors complaining about noise from the huge flying beasts (the Chinook can carry 55 soldiers), the flyers frequently seek out alternatives to practice in.
Earlier this month, William took a Chinook from his "wings" ceremony via Woolwich, east London – where he picked up his brother, Prince Harry, 23 – and headed to their cousin's bachelor party on the Isle of Wight.
The RAF said that too was a routine flight that achieved part of his training (a low flight over London and a flight over water). But a source conceded privately to PEOPLE that public perception might be different.
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