Metro Exodus

You will need to set the difficulty of the game to Normal before starting the DLC or else this achievement WILL NOT unlock. Do not lower the difficulty at any point, or again it WILL NOT unlock. You change the difficulty from the main menu by going into Options > Game Opttions > Difficulty. Set it to Normal here before starting a new Sam's Story game.
 
There are three Batwing encounters in the game and they are easy enough, especially if you play on Normal and no higher, but can also unexpectedly kill you if you're not careful. You will be able to heal as much as needed, though you only have five medkits at most for the first two encounters. You can also save beforehand, which is strongly recommended that you do. You can reload your save BEFORE dying to have another attempt at the Batwing encounter should you feel it's not going very well and that you may die, so having a save before it could allow you to retry/rethink your strategy before trying again. If you do die, reloading your save will not matter since the achievement will then be void. You must reload your save BEFORE dying to have another chance.
 
The first Batwing encounter is near the very beginning after meeting the captain and sliding down a fast rope, you will be trapped on a small platform with a train car in the middle, that will provide decent cover for you. Here the Batwing will rise up in the sky, then charge at you. If you deal enough damage to it, it will drop down and not charge, only it's smaller minions might bother you then, but they do comparatively little damage. There are some boxes in the open doors of the train car with ammo and medkits too, so be sure to grab them. This is the easiest of the encounters and will only take downing the Batwing a few times, before the fight ends via cutscene.
 
The second encounter is possibly the most difficult since you can be killed by a game mechanic during the fight. You will be in a scrap yard filled with old cars and the Batwing again will drop down below them, then shoot up in the sky, then charge at you. You can again nullify this charge by dealing enough damage to it to drop it from the sky. Here, incendiary rounds with the Sammy Rifle will be very useful and devastatingly effective against the Batwing. The mechanic you need to be aware of; after a short while, the Batwing will drop behind a pile of cars, then you will see a dust cloud coming from the pile. After a few moments, it will push those cars foward, making the arena a little smaller. This happens twice in the fight. If you happen to be in the path of these cars when they're knocked over, you will be instantly killed and potentially void this achievement, so you need to be very careful of this happening.
 
The third and final encounter is towards the end of the DLC and will be in a small grove surrounded by trees. Here, the Batwing will run around the outside, out of your view, then reveal itself before charging you a moment later. You can track the movement of the Batwing in the trees as you can see the trees moving as it runs through them, though it can be somewhat difficult to see, it's the only tell to know where it's coming from. As with the previous encounters, enough damage to the Batwing before it charges you will make it stumble and miss it's attack.
 
After beating all three encounters with the Batwing on at least Normal difficulty, the achievement will unlock after completing the story, not after the final encounter.