Stairways are notorious danger areas. An opponent could be around any corner; on landings, above you firing down or below you firing up. If you follow these lessons, you well know that there are numerous methods for handling any given tactical scenario; this holds true for how to negotiate a stairwell. I am going to give you but one example.
The following is a basic two-man method used to advance up a stairwell. Two operators ascend side-by-side, the point man covering the forward area (stairs and landings ahead) while the partner advances backwards covering upper landings and railings. It is important that they synchronize their steps, one step at a time while NEVER crossing their feet or legs (trip hazard).
As the pair reach and clear the landing, they slice-the -pie onto the next flight of stairs and secure the landing.
Now, depending on how many team members you have, you are ready to move some more people up onto the next landing. When your team is staged on the next landing its a matter of “lather-rinse and repeat” until you reach the top. If you are practiced at this technique it will look like a smooth and fluid movement with no pauses. Once the point team is on the landing the next operators simply advance and keep up.
Depending on the tactical situation you may wish to leave an operator on the top and bottom of each stairwell to prevent an opponent from coming up behind you.