In a letter to customers and investors, Eclipse Aviation CEO Vern Raburn on Monday addressed concerns that the company has not yet delivered its first aircraft -- an event that has been anticipated for weeks. "That important milestone event has not yet taken place and in turn, this may be impacting your confidence that Eclipse can perform, and more importantly, meet the schedules we have projected for delivering your aircraft," Raburn wrote. "Some of you have specifically asked whether it will still be appropriate for us to invoice for the upcoming 60-percent progress payment due for aircraft scheduled to be delivered through June 30, 2007." In a lengthy letter, Raburn explains the complexities addressed by the company as it evolves from development to production, and assures customers that they will still get their airplanes on time. "We are positioned with an achievable plan to deliver approximately 10 aircraft in 2006 and 515 aircraft in 2007," he says. Thus, the required progress payments from customers are still expected on schedule.