By John Crawley WASHINGTON, May 28 (Reuters) - A federal board set up to oversee government loan guarantees to airlines hit hard financially by the Sept. 11 attacks said on Tuesday it had rejected a $15 million request from Vanguard Airlines Inc.(VNGD). Despite a revised proposal by the small airline, the Air Transportation Stabilization Board said it rejected the plan in a unanimous vote last week because Vanguard could not assure the government that it could repay the loan. Kansas City-based Vanguard, which flies to 17 cities with 14 jet aircraft, said it planned to revise its loan guarantee application for a second time. The airline also confirmed that it was seeking additional help from private markets, which have become more accessible to airlines than they were in the months immediately after Sept. 11. "We intend to continue to work with both the (board) and the private investment community in our effort to secure financing for the airline's future," Scott Dickson, Vanguard president and chief executive, said in a statement. Vanguard raised $1.5 million in new private financing last week. The $10 billion loan guarantee program was created by Congress as part of a $15 billion airline bailout in the aftermath of Sept. 11. Vanguard has received $7.2 million in direct cash aid under that program. The top eight U.S. carriers lost nearly $9 billion last year because of the dramatic drop in demand after Sept. 11 and the recession. First quarter losses narrowed but were still huge. Vanguard lost $30 million last year and $7.5 million in the first quarter, compared with an $11.5 million first quarter loss in 2001. The airline, which has reduced its losses as part of a revamped business plan, filed its initial loan guarantee application last December for $60 million. It reduced that figure to $15 million in a revised filing earlier this month. The company said its first application was based on a grimmer business scenario than it actually experienced this past winter. Vanguard would not detail what the stabilization board wanted in return for approval, but a spokeswoman said the company has offered the government a stake in the company. She would not disclose that figure. In its only other decision, the stabilization board approved a $380 million loan guarantee for America West Airlines (AWA) in December. America West pledged $1.2 billion in concessions and gave the government the right to buy a one-third stake in the company. America West had to file its application several times before satisfying government concerns. US Airways (U) plans to seek $1 billion in loan guarantees, while United Airlines, a unit of UAL Corp. (UAL) is considering a bid for federal help. All applications are due by June 28, but Congress may delay grants from the program until next Oct. 1 to help pay for other spending priorities. The Senate is due to take up that proposal when it returns from its Memorial Day recess next week. The stabilization board is comprised of representatives from the Federal Reserve Board, the Treasury Department and the Transportation Department. ©2002 Reuters Limited.