When climbing or descending what are the highest angles that can be achieved before great discomfort would be felt for the passengers? In other posts you have mentioned that about 3 degrees is the normal decent rate this "sounds" low although there is a difference between slowly coming to the airport and dropping like a stone.
Pitch attitudes are never large, except for just after take off. In the case of the 767, at light weights, on a domestic sector, the initial pitch attitude after take off can be has high as 25 degrees. But, once clean up altitude is reached, the attitude is reduced to about 5 degrees to accelerate, and then back to about 10 for the climb. Eventually, as you reach the cruising altitude the attitude will have reduced to about 4 degrees. In level cruising flight the pitch is about 3 degrees nose up.
In the case of the A380, the initial attitude after take off is normally about 12 degrees. It's reduced to 10 for the gear retraction (the open doors create a lot of drag), and then back to 12 until we reach clean up height. After the flaps are retracted, pitch will be about 7 degrees, and will again reduce to about 4 as we approach cruising altitude. Pitch in the cruise is about 2.5 degrees nose up. At very light weights, the sort of thing you see on empty short range ferry flights, the initial pitch could be up to another 10 degrees higher.
These attitudes often feel much steeper though, because they are associated with large amounts of power, and often rapid accelerations. These lead us to one of the inner ear illusions, in which an acceleration will give rise to a strong pitch up feeling. Pilots are taught to ignore these illusions when they undergo initial instrument training (in fact, if they can't, then they won't progress any further), but of course the passengers feel them every day.
Descents are also quite gentle. A normal descent from altitude will have initial pitch attitudes of around zero degrees. If the speed brakes are used to increase the rate of descent, the pitch will go down to about minus 3 degrees. Transient attitudes of less than that might be used, but not as a matter of course, and unlikely to go below minus 7 degrees. In the case of QF30, we wanted down as soon as we could, nevertheless the peak attitude was in the region of minus 3 degrees.
About the steepest stable attitude I could give you would be around minus 10 degrees, and to do that I'd need landing gear down, full speed brake, and speed near the gear max. Very uncomfortable and never used in day to day ops.
The 3 degree figure you mention in your post most likely refers to the glideslope angle. It represents the actual descent angle achieved by the aircraft, but the pitch attitude to fly it will be around 2-3 degrees nose up (in 767/747/380).
One of the criticisms that's often thrown at Airbus is that the flight control system will interfere, and not allow pilots to fly to the attitudes that they want. The reality is that whilst it does limit attitudes, the point at which it does so is well outside any attitude that you might reasonably need to select.
