US Airways Group Inc. told investors and regulators its business is being hurt by a dispute with the union representing its 10,000 flight attendants. In a regulatory filing with the Securities and Exchange Commission, the airline said it expects a "material adverse effect" on operational results, particularly short-term revenue, from a federally mandated 30-day cooling-off period with the union and any cessation of operations that could result from a continued standoff. Passengers appear to be shying away from bookings with the airline amid the union's threats to strike random flight routes beginning March 25, the end of the cooling-off period. In a separate letter to investors, the Arlington, Va.-based carrier said it expects its load factor, a measure of revenue from seat sales against availability, to fall 6.5 percentage points in March, 5.5 points in April and 3.0 points in May, over the same periods a year earlier. The Assn. of Flight Attendants has said it will implement random strikes in several cities, including Los Angeles, if the cooling-off period ends without a deal. Talks are set to resume Friday. US Airways shares gained $3, to close at $23.75 on the NYSE.