This winter skiers and snowboarders will be able to fly to Mammoth for the first time in years. Tickets go on sale Monday for new Horizon Airlines service from LAX to Mammoth Lakes. The airline plans to run one nonstop flight per afternoon each way, from Dec. 18 until April 12. Previous air service to the Eastern Sierra from Los Angeles has never lasted, but the runway at Mammoth Lakes has been closed this summer for extensive improvements.