I suggest using a jet aircraft that has a top speed of around 1000 mph.

I got a bomber for the job aka the b121

I got in by flying in from behind with a helicopter@pepinoscom

@SpeedDemon348 another plane/helicopter that can be used for that? Randomusername deleted almost every post, including the Jet Ranger.

1. Download randomusername's Jet Ranger helicopter because it cant be hit with misiles and just maneuver your way into the base.

Another possible way,

1. Use any possible plane that takes off easy, lands easy, spawns in air easily, and speeds up in air easily. (Twin Prop
   recommended)

2. Spawn at “Ice Base Assault”

3. Approach the base

4. Before the targeted missiles hit you, go to menu and press restart, here.

5. Repeat that until you have landed in the base.

6. You do not need to land perfectly, if you land with your gear going up the wall, save the location.

7. Get a car such as little bugger and drive to the end to the runway the set that as the actual location.

8. Delete the old location

9. You won’t be attacked by the missiles if your respawn and take off.

10. Ya dun!

Heh... How I unlocked the base:
1. Start at Ice Base Assualt with a fast plane; 700-800+ mph. I haven't done much testing with this, so go for that range or higher
2. Fly really high
3. When you get over the base, do a sharp nose dive
4. Crash into the wider part of the base closer to the mountain
5. If you're lucky, your cockpit should glitch through the roof of the base and stop inside the runway; you should be going too fast for collision detection to work properly
6. Use a car and drive to the hangar inside the base.
7. ???
8. Profit

I drove a plane and dropped the go cart on top and got in after setting like 10 custom locations on top of the base p.s.it's a good idea to come from behind the base rather than head on

@RAF1 ok

@RailfanEthan Is eliminating the missile launchers pivotal?

Or, you could just climb to about 50-60 thousand feet, fly above the base, complete an "inverted split s" and use SunnySkies's anti shipping missiles to target the SAMs. The lasers shouldn't be able to target your missiles whilst in a vertical dive. One of said missiles has the explosive blast to knock out all of the base defenses. Once you are done, execute a nice landing and save the location. It also might save the hidden base automatically as a discovered location.
@RailfanEthan
@DandruffCat
@Testin123
@BoxGlow
@Swiftsure
@KingDeadshot
@NativeChief1492

@KingDeadshot i mean like a in game unlock, i thought you cant

Well, you cant. But you can go to the bottom of its mountain and find a dock called undermountian docking bay.

Create a reasonably maneuverable boat ---> Attach the main cockpit below the water line (e.g. submerged) ---> peacefully swim towards the ship dock at the base of the mountain and unlock the base from there..
.
This is how i unlocked that location an update ago, though for added challenge i did not put my cockpit underwater so i had to snipe the turrets using rocket launchers first.

Tip:Use "restart here" when a missile is about to hit you. You don't need to make a perfect landing. Just a crash landing would do it. Unfortunately for me, I forgot to take out the turrets, so it doesn't work for me.

I just get a fast plane and fly towards it. When the missiles get near, I do restart here and eventually crash in the base. Worked for me.

1. Eliminate missile launchers
2. Land inside the mountain/tunnel.
3. Set a spawn location (custom)
4. If you want the actual base location, drive a car around the inside of the base.
   Little know fact: At the bottom, at the river, there's a submarine dock.