Frontier asks for loan guarantee, sees qtrly loss Friday June 28, 2:56 PM EDT DENVER, June 28 (Reuters) - Regional air carrier Frontier Airlines (FRNT) asked the federal government on Friday to secure 85 percent of a $70 million line of credit, as part of a $10 billion airline relief program created after the Sept. 11 attacks to aid the faltering industry. The Denver-based low-fare carrier also said that while it had expected to break even in the current quarter, a slower-than-expected return in demand from business travelers would now lead to a loss for the period. Frontier said it needed to apply for a government loan guarantee to compete with airlines that have kept up with "unsustainable business models," despite the excruciatingly slow recovery in business travel since Sept. 11. "Many airlines are operating at extremely high breakeven load factor levels as a result of excess capacity and limited demand, with little or no apparent hope of near-term profitability," Frontier said. The airline said it would use the additional credit to boost its liquidity, and said its ability to post a profit in the quarter immediately after Sept. 11 demonstrated that it had a viable business plan. Roger EWROPS