Hi, I am living next to Vienna in the famous Vienna woods. A very beautiful area in mid of woods (obviously) and hills which arrive up to almost 600m ASL.
When I fly with my Mini 3 Pro my starting point is my terrace which is at a height of 370m ASL.
My drone just before take off is registering the GPS coordinates  of the starting point and putting the height on zero meters. The max. height the Austrians may fly is 120 meters above ground level. This is more or less the height all countries  of the EU may fly in their countries.
If I have set the Mini 3 Pro to a max height  of 120m and the next hill I want to reach has a height of 500 meters I am going to have a problem as the max. height my drone will reach is 120 meters above the starting point, which equals to 490 m ASL, so with this preadjustment my drone cannot overfly this hill. OK, someone could advice me to  adjust my  drone to a height of 280m, then I could overfly this hill of 600m with a safety of 50 meters but then however I have no guarantee that my drone would climb before reaching this hill to a height of more than 120 meters above ground, which unfortunately is forbidden.
I hope I could explain understandeable the problem and hope that someone can help me out to find a clever solution for this threat.
Thanks   

Nah, its legal to fly 120 above the ground below, so flying up that hill is no problem as long as the height drone<>surface below < 120 meter.
But drone will not fly higher than 500 meters from any start position. Forget all about ASL ect.

Barometric height is set to zero at start of a flight, from your garden it shows zero in the app at takeoff, same for taking off top of that hill.

cheers
JJB

Just imagine a weighted string 120m long attached to the bottom of the drone.
The "120m above the ground beneath the drone" rule ( AGL) means that that string must always be in contact with the ground beneath the drone.
The actual height relative to the take off point is irrelevant as far as the law is concerned.
That said, you might want to check whether the rule is "within 120m of the closest ground" which would mean that that string would have to touch the ground SOMEWHERE but not necessarily beneath the drone, meaning ..... you could fly the drone up a 200m vertical cliff face to more than 120m AGL PROVIDING the drone was always within 120m horizontally of that cliff face.

Hi JJB,
You are right, however my problem is, that I do not know in which height I am flying up that hill. The only height indicated is the difference of my starting point and the height I am just now flying. So if I have a height of 50m indicated on the screen of my transmitter means I am 50m above my starting point which does not tell me anything. If the ground where I am just flying is also 50m above my starting point I am going to crash with the surface.

645peter Posted at 1-24 01:37
Hi JJB,
You are right, however my problem is, that I do not know in which height I am flying up that hill. The only height indicated is the difference of my starting point and the height I am just now flying. So if I have a height of 50m indicated on the screen of my transmitter means I am 50m above my starting point which does not tell me anything. If the ground where I am just flying is also 50m above my starting point I am going to crash with the surface.

So if I have a height of 50m indicated on the screen of my transmitter means I am 50m above my starting point which does not tell me anything.
Knowing your drone's height relative to the launch point isn't nothing.
It's a big help to work out the height of the drone above where it it.
You just have to estimate.

645peter Posted at 1-24 01:37
Hi JJB,
You are right, however my problem is, that I do not know in which height I am flying up that hill. The only height indicated is the difference of my starting point and the height I am just now flying. So if I have a height of 50m indicated on the screen of my transmitter means I am 50m above my starting point which does not tell me anything. If the ground where I am just flying is also 50m above my starting point I am going to crash with the surface.

yes, it is not that easy fo fly drones...  ;-)

And flying within Line Off Sight i reckon you can make a good height guess
flying your drone up that hill.

cheers
JJB