I discovered what the mystery airplane was, an Airtran DC-9 bound for New Orleans. I got out my telescope and saw dark green engines and a giant white A on the tail. At first, I thought it had blue engines. The plane looked like it was at about 10,000 feet. Airtran also serves my local airport in Gulfport. The Boeing 717 will begin service to my area soon. I also aimed my telescope at a contrail and saw a red Northwest A-320. I used Northwest route maps to figure out where it was going. Memphis to Cancuan Mexico.
Ocean Springs, MS