Federal Aviation Administration chief Steve Dickson told staff late Wednesday that he is resigning after just over two-and-a-half years in the post for family reasons. Citing “mixed emotions and a heavy heart,” the FAA administrator said the decision was difficult. “Over the past several years, my family has been a source of tremendous encouragement, strength and support,” Dickson, 64, wrote in a memo to staff. “Nevertheless, after sometimes long and unavoidable periods of separation from my loved ones during the pandemic, it is time to devote my full time and attention to them. As I wrote in …