at a premium price, would sit in regular economy class seats for take-off and landing, and move to the crown area during flight. However, pricing feasibility studies found the SkyLoft concept difficult to justify. In 2007, Boeing dropped the SkyLoft concept in favor of upper-deck galley storage options, which were favored by the airlines. Outfitting the crown space for sleeping remains an option on VIP aircraft, and the first 747-8 BBJ with AeroLoft was produced in 2012. The first order for the 747-8 Intercontinental was placed by an undisclosed VIP customer in May 2006. Lufthansa became the first airline to order the 747-8 Intercontinental on December 6, 2006. In December 2009, Korean Air announced the order of five 747-8Is. Boeing stated firm configuration for the −8 was reached in November 2007. Major assembly of the first 747-8 Intercontinental began on May 8, 2010. Assembly of first 747-8I was completed in February 2011, before being unveiled at a rollout ceremony in Everett, Washington, on February 13, 2011. At the time, deliveries were planned to begin in late 2011. Following gauntlet ground testing the 747-8 Intercontinental's first flight occurred on March 20, 2011, from Paine Field in Everett, Washington. The second 747-8I first flew the following month. After the flight test program the 747-8I was FAA certified on December 14, 2011. At that time, −8I deliveries were planned to begin in early 2012. During development testing, aeroelastic flutter was observed during a test that measured how the aircraft performed if its wing-to-strut join fitting fails at the same time the fuel tanks in the horizontal stabilizer were filled at over 15% of their capacity. To meet FAA regulations, Boeing reported in January 2012 that the 747-8's fuel tanks in the horizontal stabilizers would be closed off to prevent their use until the flutter condition can be resolved; this reduced range by . On December 18, 2013, Boeing announced that a series of new performance packages will allow for the reactivation of the tail fuel tanks by early 2014. Earlier 747-8s can also be retrofitted with them. The first 747-8 Intercontinental was delivered to a VIP customer on February 28, 2012. It was to be outfitted with a VIP interior before beginning service in 2014. The first 747-8I was delivered in May and began commercial service on June 1, 2012, with Lufthansa. U.S. Presidential aircraft In 2007, the United States Air Force was