for the memorial. Ground was formally broken in September 2004. Construction of the spires began in February 2006 and was completed in seven months. The memorial was dedicated on 14 October 2006, with about 30,000 people attending. The keynote address was delivered by President Bush, a former F-102 Delta Dagger pilot with the Texas Air National Guard. The first official ceremony at the memorial was held the next day: Secretary of the Air Force Michael Wynne laid a memorial wreath beneath the spires for fallen airmen. To all who have climbed sunward and chased the shouting wind, America stops to say: your service and your sacrifice will be remembered forever, and honored in this place by the citizens of a free and grateful nation. — President George W. Bush at acceptance ceremony. In April 2017, the day-to-day operations of the Air Force Memorial were transferred to the Air Force District of Washington. The Air Force Memorial Foundation, the organization created to plan for and build the Memorial, continues today as an affiliate of the Air Force Association. Design The three memorial spires range from to high and appear to be soaring; its array of stainless steel arcs against the sky evokes the image of "contrails of the Air Force Thunderbirds as they peel back in a precision 'bomb burst' maneuver." Only three of the four contrails are depicted, at 120 degrees from each other, as the absent fourth suggests the missing man formation traditionally used at Air Force funeral flyovers. The spire structure consists of stainless steel plates with high-strength concrete filling the lower 2/3 of each spire. The upper third is hollow stainless steel. At the transition between concrete and hollow steel portions, dampers provide aerodynamic stability and dissipate wind sway energy. Each damper consists of a lead ball weighing about a ton that is allowed to roll inside a steel box. The structural design of the spires was completed by the Arup engineering consultancy. Pedestrians approach to the spires from the west. South of the approach, before the inscription wall, stand four bronze statues representing the United States Air Force Honor Guard, sculpted by Zenos Frudakis. To the north, a stone plaza leads you to the glass contemplation wall, a free-standing glass panel with the images of four F-16s flying in a Missing man formation engraved on both sides of the 5-ply panel. Except for the information kiosks