people say that suiciding in the name of allah is acceptable, but from what i heard, its haraam no matter what because its still suicide

people say that suiciding in the name of allah is acceptable, but from what i heard, its haraam no matter what because its still suicide. I heard this story that 2 countries were fightiing, one muslim, the other non-muslim. and 2 guys got into a helicopter and then one of them turned out to be a spy from the enemy's side, so the enemy (non muslim) had a gun and told him to fly the plane to his country or else he would kill him (to fly the helicopter), but the muslim instead he just made the plane crash intentionally, is this considered suicide? becuz it would have been surrendering to the non-muslim side , when someoen is suiciding in the path of allah, and sacrificing their lives only for the sake of allah (by suiciding) is this okay? becuz from what i heard this is haraam and suicide, no matter what the intention is, is always wrong.

second question: consequences of backbiting ( all my good deeds are gone and the sins one the person i backbited are mine)does this consequence fit in when one backbites a non-muslim, or is it the same consequences whether the person who one is backbiting about is muslim, or non-muslim (becuz in recall a hadith saying that one shud not backbite his/her brother, but if he/she is not muslim, then would it matter?