Here is a tip for you, "SAVE" before you send your Firebird out on a mission. Do this ALWAYS !! If your attacked and it goes down...just reload, then use your geoscape time function...wait a few minutes...hours...whatever...and try sending it out on the mission. If you time it right the UFO shooting you down, will have moved on to some other area and your Firebird and crew will be fine.
Good idea anyhow, is to save right before doing every mission, as if you get wiped, or lose a team member that you like / want you can just reload and go again.