Every now and then...maybe once or twice a month I have to land via an ILS (more often in winter than summer). Most of the time those are flown to a visual.
Even more rarely things are just bad....and I get to fly and approach....but the Captain has to land.....a Category II approach.
Things happen fast during an approach. With a Category II approach things can get messy fast.
At MY company this is how we fly Cat II approaches (Cat short for Category).
The Captain briefs the approach and the First Officer flies the approach. The Captain is looking outside from 500 feet down to (hopefully) the runway. The First Officer is looking inside the entire time.
The decision height for MOST Cat II approaches is 100 feet above the runway. If the RUNWAY is not visible at 100 feet a missed approach much be executed.
Things happen fast.
In the simulator during training (the only place I've shot a Category II approach to mins), a moments hesitation can really mess things up.
The time is takes the plane to descend from 100 feet to the runway is 5 seconds. When I'm flying the approach and I hear "Approaching Minimums!" my fingers are positioned right over the Go Around buttons.
Once I hear "Minimums! Minimums!" I take a breathe and, if I don't hear "landing" from my Captain, I push the Go Around buttons and execute a missed approach.
The first time my Captain and I shot a Cat II approach he hesitated for a moment at minimums. That hesitation caused me to go missed approach when in reality he had the runway in sight.
After going missed we were vectored back around. This time he was ready and said "landing". Up until that point the autopilot was engaged. I had my hands on the thrust levers and yoke as a backup. The autopilot MUST fly the entire approach. Once I heard "landing" I immediately put my hands in my lap and looked outside.
I can only imagine how difficult it is to take over the controls of an airplane with just 5 seconds until landing.
Another scenario is a balked landing during a Cat II approach. This is where the Captain takes over but right before touchdown tower calls a go around. Things are really busy as now the Captain is flying and I am the pilot monitoring. So he flies the missed while I push the buttons. Once level I take over the controls again.
At "mainline" and newer regional jets a Heads Up Device is used on the Captains side so they can scan the instruments and look outside the entire time.
Also more common at mainline are aircraft setup for Cat III approaches. A Cat III approach is one where the autopilot flies the approach and lands the aircraft.
One day I will get to experience the pure