An escalation contract means that you will have to do the same mission 5 times and after each successful run there will be an extra objective added to the existing list of objectives.
To get the achievement you have to complete an ICA Facility escalation from level 1 to level 5.
To launch a escalation contract for the ICA Facility go from the main menu to the Destinations tab, select ICA Facility the 1st option and go all the way to the right where you'll find 2 options.
I found easy to do the 2nd option.The Snorrason Ascension
1.Kill Cilas Netske with a pistol wearing a Soviet Soldier disguise*You can use 47's pistol*.
2.Break into the safe and steal the contents *I used the crowbar to open it ,you find it at the starting location on the right*
3.Kill Moses Butusov wearing Airplane Mechanic disguise *You can get one from a bench in the changing room/Locker room*.
4.Hide all the bodies in 90 secs or you fail the mission.
5.Do not pacify anyone else you fail.Below more detail guide with pictures
1. Go right and get the crowbar , vault the fence.
2. Go right and vault the next fence in front of you.
3.You will see the generator on the left , pass it and go through the window *the guard won't noticed you, just keep to the left*.
4.When inside turn right and open the door , go straight and open the next door in front of you *this is the VESTUARIO room* go steal the Airplane Mechanic Disguise.
5.Now you are not trespassing so we can walk with no issues to the COMANDANTE room upstairs.
6.Swap to your Fiber Wire and wait till the target will be walking away and garrote him.
7.Carry him to the toilet and drop him there.
8.Swap to his clothes Soviet Soldier.
9.Swap to ICA19 weapon and wait for the target to come.
10.When his alone head-shot him and drag his body to the toilet room and hide him in the same box.
11.Break the safe when there is no one and loot the Vodka.
The achievement should pop now