Looking for my dad - African American/Hawaiian - Allen? - helicopter - mother name is Mai Tran- born in Tah Ninh 1968

Hello...My name is Sarah Michel, I was born in 1968 in Vietnam, my real name is My Thuong Tran, and my mother's name is Mai Tran. I have never known who or where my father is. My mother told me that he was a helicopter pilot, had a Hawaiian and an African American background, and that he knew her to be pregnant with me, but that he left Vietnam before I was born. His name had to do with Allen or Alan... As for my mother, I met her before, after I was adopted by a family in Michigan, but after she moved the last time, I lost track of her as well. She was living in San Diego, CA with my sister, Huong, and my brother Kai. Can anyone help me? Thanks!