Noticing the question of Cabin altitude, said to be 8,000' but at least into the 90's was 5,000'. Any one have input as to why the change?

My company used a cabin altitude of 9500' for a while, in the 1980s. It was supposed to give some fuel savings. We had a lot of "accidental" mask deployments, as crews pushed the envelope, so they eventually went back to 8,000.

Profit is always more important than safety, passenger comfort, or employees.

40 years in the airline industry.

Cabin pressure is actually a bit of a "movable feast"

In virtually all airliners the cabin pressure at cruise is around 8000 ft at standard atmosphere, and always has been for jets, for as long as I have been flying, which well predates the 1990s.

However, of course the pressure takes a little while to get that high as you ascend, at 25,000 feet for instance, the cabin pressure will be at a somewhat lower altitude. If you cruise low you may well be at 5000 ft of cabin altitude but it will increase in altitude and decrease in pressure as you climb.

The big issue is "differential pressure" ie, the pressure inside vs the pressure outside. A 10 psi differential pressure puts a large strain on aircraft structures, so there are limits to how much you can pressurize an aircraft. 8000 feet is safe for most people and safe for all airplanes which can go high enough for it to be an issue..

If you were going to pressurize an aircraft to 5000 feet at cruising altitude, the differential pressure at 40,000 feet would be far higher than most current aircraft are built to withstand, the aircraft would have to be far stronger and therefore heavier.

You could get round this differential by flying lower, so the external pressure helps to counter the internal pressure, and since most turbo-props do indeed fly lower, typically around 23-25,000 feet, it may well be that for some of them 5000 feet cabin altitude is the norm. They will have a differential pressure limit which allows that degree of pressurization.

It is more than 30 years since I last flew a turbo-prop airliner and I can't recall that detail.

However, I do not recall any high altitude jet, that I have ever known of, which is pressurised to 5000 feet at normal cruising altitude.

That said, I believe the B787 can be pressurised to 6000 at 35,000 feet