What is REALLY new about "complex" aircraft?

Really easy...

Quite easy indeed when you are flying in more or less constant conditions (TAS, wind). But descending from cruise at FL 380 to a landing at sea level, the air density increases by a factor of three, TAS will drop less than one quarter and the wind may change from 100KT to 10KT and change direction by as much as 180 degrees. Picking a good starting value for a constant descent is really more an art than anything else...

descending from cruise at FL 380 to a landing at sea level

I somehow suspect that the average pilot joining the circuit at Shoreham is unlikely to struggle with this problem...

I found that when I started to fly high regularly (not THAT high, I like cruising at FL180), I developed a sense of "vertical awareness" that I did not have (nor needed) before. Also, a very helpful tool is what my wife calls the "Are we nearly there yet?" screen with the flight planned route and the time remaining to the destination. If the time to the IAF waypoint approaches twice your altitude, it is about time to prepare for the descent if the descent rate is to be 500-1000 ft per minute.

I once sat in an aircraft that had a little line across the track on the MFD where you reached the bugged altitude, that was fantastic to just eyeball it. But that was an A320, IIRC.

I once sat in an aircraft that had a little line across the track on the MFD where you reached the bugged altitude, that was fantastic to just eyeball it. But that was an A320, IIRC.

Proline 21 does that on CJ's etc

Proline 21 does that on CJ's etc

Almost every glass cockpit does that in one way or another. Ours generates a waypoint named "#TOD". But many of these systems (at least the ones I have used or looked at) do not take into account the decrease in TAS with altitude, so following it blindly will result in an early arrival at the lower levels (with significant increase in fuel consumption).

I mean the other way round - a little indicator that shows you where you will reach the altitude you have currently bugged on the PFD.

But you are right, that does not take into account changing wind, either.

Peter that with the descent planing is a good example but only one peace of cake. With a HPA you get a lot of things to work on it: Prob, cowl flaps, gear, AP, GPS, one more trim, engine managment (EDM, FuelFloe, totalizer), fuel switch (not only both), mixture, maybe a PFD! Every point is not a challange, all together with more speed and power it needs good work flow!

I mean the other way round - a little indicator that shows you where you will reach the altitude you have currently bugged on the PFD.

Most systems do both: The suggested top of descent and once you are in descent (or climb) a point or radius by which you will have reached the preselected altitude.

Peter, are you referring to the EASA term "complex aircraft"? Because that is different to what people believe a complex aircraft is.

Would you consider the Twin Otter to be complex for instance? Twin, turbine, cruise at 180+? In the EASA world it isn't complex in fact. The Pilatus PC12 also isn't complex, just high performance.

I believe that "complex" is when you have more to do than you're used to, so for some it's complex enough to remember gear and prop. For others, complex is to manipulate a missile guidance system while screaming along at 600 kts 100ft above the deck.

Actually that was a typo, the TwinOtter is complex per the EASA definition as you say. The Otter is not.